Hey there,

I was installing arch linux onto my pc, besides windows 7,
as I accidentely unmounted the boot partition of windows. Does anyone have an idea how to remount and where to mount it? Allready tried "mount /dev/sda1 /mnt" but by booting windows it only keeps saying "Missing operating system".

Any help would be really great. Thanks in advance, Julien

Sounds like you removed it, not "unmounted" it.
Go to bootinfoscript and download the script - run it and post the RESULTS.txt as it says.
Looks like it is also in AUR if you have that enabled.

Sorry for taking so long. Hope it's anyhow possible to get windows back to work




Boot Info Script 0.75 [14 November 2016]


============================= Boot Info Summary: ===============================

=> Grub2 (v2.00) is installed in the MBR of /dev/sda and looks at sector 1 of
the same hard drive for core.img. core.img is at this location and looks
for (,msdos3)/boot/grub. It also embeds following components:

modules
---------------------------------------------------------------------------
fshelp ext2 part_msdos biosdisk
---------------------------------------------------------------------------

sda1: __________________________________________________________________________

File system: ext4
Boot sector type: -
Boot sector info:
Operating System:
Boot files:

sda2: __________________________________________________________________________

File system: ntfs
Boot sector type: Windows 7/2008: NTFS
Boot sector info: No errors found in the Boot Parameter Block.
Operating System:
Boot files: /Windows/System32/winload.exe

sda3: __________________________________________________________________________

File system: ext4
Boot sector type: -
Boot sector info:
Operating System: Arch Linux
Boot files: /boot/grub/grub.cfg /etc/fstab
/boot/grub/i386-pc/core.img

sda4: __________________________________________________________________________

File system: swap
Boot sector type: -
Boot sector info:

============================ Drive/Partition Info: =============================

Drive: sda _____________________________________________________________________
Disk /dev/sda: 465.8 GiB, 500107862016 bytes, 976773168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos

Partition Boot Start Sector End Sector # of Sectors Id System

/dev/sda1 * 2,048 206,847 204,800 7 NTFS / exFAT / HPFS
/dev/sda2 206,848 771,971,071 771,764,224 7 NTFS / exFAT / HPFS
/dev/sda3 * 771,971,072 973,297,663 201,326,592 83 Linux
/dev/sda4 973,297,664 976,773,167 3,475,504 82 Linux swap / Solaris


"blkid" output: ________________________________________________________________

Device UUID TYPE LABEL

/dev/sda1 bf260e0b-9853-4d58-b7e9-4f9060e5b2e3 ext4
/dev/sda2 4A76D09D76D08B59 ntfs
/dev/sda3 9fb735f8-9d4f-4610-aa39-5107ed82a212 ext4
/dev/sda4 c43a4d6c-0758-4c0a-b309-d7fbd22c5eab swap

========================= "ls -l /dev/disk/by-id" output: ======================

total 0
lrwxrwxrwx 1 root root 9 Mar 19 17:42 ata-HL-DT-ST_BD-RE_BH30N_M00AATK1935 -> ../../sr0
lrwxrwxrwx 1 root root 9 Mar 19 17:42 ata-WDC_WD5000AAKS-07V0A0_WD-WCAWFA834549 -> ../../sda
lrwxrwxrwx 1 root root 10 Mar 19 17:42 ata-WDC_WD5000AAKS-07V0A0_WD-WCAWFA834549-part1 -> ../../sda1
lrwxrwxrwx 1 root root 10 Mar 19 17:42 ata-WDC_WD5000AAKS-07V0A0_WD-WCAWFA834549-part2 -> ../../sda2
lrwxrwxrwx 1 root root 10 Mar 19 17:42 ata-WDC_WD5000AAKS-07V0A0_WD-WCAWFA834549-part3 -> ../../sda3
lrwxrwxrwx 1 root root 10 Mar 19 17:42 ata-WDC_WD5000AAKS-07V0A0_WD-WCAWFA834549-part4 -> ../../sda4
lrwxrwxrwx 1 root root 9 Mar 19 17:42 usb-Generic-_Compact_Flash_20060413092100000-0:0 -> ../../sdb
lrwxrwxrwx 1 root root 9 Mar 19 17:42 usb-Generic-_MS_MS-Pro_20060413092100000-0:3 -> ../../sde
lrwxrwxrwx 1 root root 9 Mar 19 17:42 usb-Generic-_SD_MMC_20060413092100000-0:2 -> ../../sdd
lrwxrwxrwx 1 root root 9 Mar 19 17:42 usb-Generic-_SM_xD-Picture_20060413092100000-0:1 -> ../../sdc
lrwxrwxrwx 1 root root 9 Mar 19 17:42 wwn-0x50014ee158f72e4d -> ../../sda
lrwxrwxrwx 1 root root 10 Mar 19 17:42 wwn-0x50014ee158f72e4d-part1 -> ../../sda1
lrwxrwxrwx 1 root root 10 Mar 19 17:42 wwn-0x50014ee158f72e4d-part2 -> ../../sda2
lrwxrwxrwx 1 root root 10 Mar 19 17:42 wwn-0x50014ee158f72e4d-part3 -> ../../sda3
lrwxrwxrwx 1 root root 10 Mar 19 17:42 wwn-0x50014ee158f72e4d-part4 -> ../../sda4

================================ Mount points: =================================

Device Mount_Point Type Options

/dev/sda3 / ext4 (rw,relatime,data=ordered)


=========================== sda3/boot/grub/grub.cfg: ===========================

--------------------------------------------------------------------------------
#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
insmod part_gpt
insmod part_msdos
if [ -s $prefix/grubenv ]; then
load_env
fi
if [ "${next_entry}" ] ; then
set default="${next_entry}"
set next_entry=
save_env next_entry
set boot_once=true
else
set default="0"
fi

if [ x"${feature_menuentry_id}" = xy ]; then
menuentry_id_option="--id"
else
menuentry_id_option=""
fi

export menuentry_id_option

if [ "${prev_saved_entry}" ]; then
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
fi

function savedefault {
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
}

function load_video {
if [ x$feature_all_video_module = xy ]; then
insmod all_video
else
insmod efi_gop
insmod efi_uga
insmod ieee1275_fb
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
fi
}

if [ x$feature_default_font_path = xy ] ; then
font=unicode
else
insmod part_msdos
insmod ext2
set root='hd0,msdos3'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos3 --hint-efi=hd0,msdos3 --hint-baremetal=ahci0,msdos3 9fb735f8-9d4f-4610-aa39-5107ed82a212
else
search --no-floppy --fs-uuid --set=root 9fb735f8-9d4f-4610-aa39-5107ed82a212
fi
font="/usr/share/grub/unicode.pf2"
fi

if loadfont $font ; then
set gfxmode=auto
load_video
insmod gfxterm
fi
terminal_input console
terminal_output gfxterm
if [ x$feature_timeout_style = xy ] ; then
set timeout_style=menu
set timeout=0
# Fallback normal timeout code in case the timeout_style feature is
# unavailable.
else
set timeout=0
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/10_linux ###
menuentry 'Arch Linux' --class arch --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-9fb735f8-9d4f-4610-aa39-5107ed82a212' {
load_video
set gfxpayload=keep
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos3'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos3 --hint-efi=hd0,msdos3 --hint-baremetal=ahci0,msdos3 9fb735f8-9d4f-4610-aa39-5107ed82a212
else
search --no-floppy --fs-uuid --set=root 9fb735f8-9d4f-4610-aa39-5107ed82a212
fi
echo 'Loading Linux linux ...'
linux /boot/vmlinuz-linux root=UUID=9fb735f8-9d4f-4610-aa39-5107ed82a212 rw quiet
echo 'Loading initial ramdisk ...'
initrd /boot/initramfs-linux.img
}
submenu 'Advanced options for Arch Linux' $menuentry_id_option 'gnulinux-advanced-9fb735f8-9d4f-4610-aa39-5107ed82a212' {
menuentry 'Arch Linux, with Linux linux' --class arch --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-linux-advanced-9fb735f8-9d4f-4610-aa39-5107ed82a212' {
load_video
set gfxpayload=keep
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos3'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos3 --hint-efi=hd0,msdos3 --hint-baremetal=ahci0,msdos3 9fb735f8-9d4f-4610-aa39-5107ed82a212
else
search --no-floppy --fs-uuid --set=root 9fb735f8-9d4f-4610-aa39-5107ed82a212
fi
echo 'Loading Linux linux ...'
linux /boot/vmlinuz-linux root=UUID=9fb735f8-9d4f-4610-aa39-5107ed82a212 rw quiet
echo 'Loading initial ramdisk ...'
initrd /boot/initramfs-linux.img
}
menuentry 'Arch Linux, with Linux linux (fallback initramfs)' --class arch --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-linux-fallback-9fb735f8-9d4f-4610-aa39-5107ed82a212' {
load_video
set gfxpayload=keep
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos3'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos3 --hint-efi=hd0,msdos3 --hint-baremetal=ahci0,msdos3 9fb735f8-9d4f-4610-aa39-5107ed82a212
else
search --no-floppy --fs-uuid --set=root 9fb735f8-9d4f-4610-aa39-5107ed82a212
fi
echo 'Loading Linux linux ...'
linux /boot/vmlinuz-linux root=UUID=9fb735f8-9d4f-4610-aa39-5107ed82a212 rw quiet
echo 'Loading initial ramdisk ...'
initrd /boot/initramfs-linux-fallback.img
}
}

### END /etc/grub.d/10_linux ###

### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###

### BEGIN /etc/grub.d/30_os-prober ###
### END /etc/grub.d/30_os-prober ###

### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###

### BEGIN /etc/grub.d/41_custom ###
if [ -f ${config_directory}/custom.cfg ]; then
source ${config_directory}/custom.cfg
elif [ -z "${config_directory}" -a -f $prefix/custom.cfg ]; then
source $prefix/custom.cfg;
fi
### END /etc/grub.d/41_custom ###
--------------------------------------------------------------------------------

=============================== sda3/etc/fstab: ================================

--------------------------------------------------------------------------------
#
# /etc/fstab: static file system information
#
# <file system> <dir> <type> <options> <dump> <pass>
# UUID=9fb735f8-9d4f-4610-aa39-5107ed82a212
/dev/sda3 / ext4 rw,relatime,data=ordered 0 1

# UUID=c43a4d6c-0758-4c0a-b309-d7fbd22c5eab
/dev/sda4 none swap defaults 0 0

--------------------------------------------------------------------------------

=================== sda3: Location of files loaded by Grub: ====================

GiB - GB File Fragment(s)

408.393573761 = 438.509260800 boot/grub/grub.cfg 2
434.241645813 = 466.263416832 boot/grub/i386-pc/core.img 1
434.234111786 = 466.255327232 boot/vmlinuz-linux 1
368.695896149 = 395.884204032 boot/initramfs-linux-fallback.img 1
368.668598175 = 395.854893056 boot/initramfs-linux.img 1

========= Devices which don't seem to have a corresponding hard drive: =========

sdb sdc sdd sde

=============================== StdErr Messages: ===============================

mdadm: No arrays found in config file or automatically

You erased the M$oft "System Reserved" partition - what in Linux we'd called /boot.

Nothing else for it but to boot your Win7 CD and go through recovery - I found an article on technet when I needed to, so a quick search should find it for you. If you don't have a Win7 CD, it used to be you could download a recovery image and use that just for this sort of situation - not sure if that is still true.
Your data, and the Win7 system is still there, you are just missing the boot code.

Before you start, reformat /dev/sda1 as NTFS (after saving anything there), and remove the boot flag from /dev/sda3 - Windows boot-loaders won't boot with two boot flags, and I'd bet the recovery environment will be likewise.