i tried to install linux mint and it said "failed loading bootloader in /target/" then in gparted i mistakenly unmounted my c drive with alot of data now when i boot my computer it shows "no such device or partation your devices needs to be repaired " unfortunately my dvd drive is not working too.Now am i able to regain all my data of my c drive?
plz help me...

Too little information. Which version of windows and which version of Mint?
Newer or older computer? UEFI/GPT or MBR? Can you boot anything, either Mint or windows, CD/DVD or flash drive?
If you unmounted your windows partition, just mount it again. Unmounting isn't going to give you the error you mention. Might be best to see the details by going to the site below and getting boot repair and running it by selecting the Create BootInfo Summary option. Don't try any repairs but post the link you get after running it.

https://help.ubuntu.com/community/Boot-Repair

i was using windows 8.1 and i installed linux mint 18 cinnamon. i could not boot any of those OS right now i am using my pc with live bootable usb of linux mintand i cannot mount my windows partation

here is the image https://drive.google.com/open?id=0B5...TYtQXVVZWtJaW8 that i get when restarting my pc and here is the summary i get with boot-repair https://drive.google.com/open?id=0B5...nZfTXJuNTdBUGs

The boot repair shows that the first partition is vfat which is usually what you have for an EFI partition. A default windows 8.1 install will be UEFI/GPT. Was the system pre-installed or did you install it? You don't have any EFI files for windows or Mint on that partition. The general install process would be for Mint to create a separate directory on this partition to put it's EFI boot files. You also have windows code in the MBR which should not be there if you use UEFI. Further down on the boot repair page, it shows sda1 as an EFI partition. It also shows sda5 as an EFI partition but it is an ntfs partition and you should not have more than one EFI partition on the same drive.

You show Grub files on sda2 but it is a vfat filesystem. There isn't any other sign of anything Linux/Mint on the system other than the flash drive files. You also are using GPT partitioning in which case windows needs to be installed UEFI and if windows is UEFI, Mint also needs to be installed UEFI.

Generally, you will see windows partitions under the /media directory in the file manager to access file. Might be under /media/mint.
Mounting the windows partition will allow you to access it but it won't do anything to make it bootable. Your setup is quite a mess and the only thing I could suggest is to try installing Mint again, see the tutorial at the Mint site below. Scroll down a bit and there are screen images and it explains UEFI which you will need. I expect you will need a windows install DVD to repair the files although there may be some other way.

https://community.linuxmint.com/tutorial/view/2191

i am not getting any thing on my mind.my laptop was preinstalled windows8 then i tried to install mint on partation sda5.the only thing i want is my data which was on my c drive of windows 8 i can see my other drive om /media/mint but i can't get my c drive on it https://drive.google.com/open?id=0B5...TNCMjhISGxHdjgplz help

As far as I know, gparted does not mount or unmount filesystems. Do you mean that you mistakenly deleted the partition containing your C drive? What does "fdisk -l" show now for partitions? Scratch that. I now see the partitions listed in the Boot Repair output, and there is a huge gap between partiton 4 and partition 5, probably a missing partition.

The tool of choice for recovering lost partitions is testdisk. It is included in many recovery packages, including my own favorite, SystemRescueCD. You can also download a standalone version, which should run in your current Linux OS.

Hi nyushan - If it can help, along with advice already given by other members here, here are my comments:

- I agree that the partitioning scheme of your hard drive is unusual.

- My guess is that your main Windows partition is either sda5 or sda8.

- sda5 is labelled in your bootinfo summary as being an ESP (EFI System Partition - a boot partition for UEFI systems ...), however the size is much larger than it should be for such a partition and it is formatted with the ntfs file system, which is impossible for an ESP (which requires a FAT file system)

- sda8 is labelled as a "Windows/linux" data partition and is formatted ntfs. This is where I would start.

So if you can boot into an OS through removeable media, as you seem to be doing, mount those 2 partitions and look to see if the files you wish to recover are there. If so, copy them to removeable media (preferable other than your boot media) and you're good to go.

If you plan on attempting another go at installing linux on this system or at reviving Windows, let us know. That is another subject altogether. I have suggested what I believe is the easiest way to recover data from your Windows partition, nothing more.

Best - let us know how things go !

woo thanks alot for you whoever helped me and tried to help me all i got my c drive and all data back with the help of testdisk "plz use testdisk whoever is having this problem this will help all of you"
thanks too all of you who replied and helped and tried to help . i appreciate your help

Great news, nyushan - Cheers !