I in stalled Linux Mint Cinnamon on a HP 450-a120 Desktop running Windows 10. After the install was complete i am only able to boot onto usb I installed Linux from. I went into boot repair and clicked on it and it says GPT Detected please create a bios _boot partition ( > 1mb ) unformatted fiole sys. bios _grub flag. I am new to Linux and don't want to mess up anything , please help!

Device Boot Start End Blocks Id System
/dev/sda1 1 976773167 488386583+ ee GPT
Partition 1 does not start on physical sector boundary.

Disk /dev/sdb: 8053 MB, 8053063680 bytes
16 heads, 60 sectors/track, 16384 cylinders, total 15728640 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
Disk identifier: 0x5cf50a1f

Device Boot Start End Blocks Id System
/dev/sdb1 * 5120 15728639 7861760 c W95 FAT32 (LBA)

Disk /dev/sdc: 320.1 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders, total 625142448 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
Disk identifier: 0xa4b57300

Device Boot Start End Blocks Id System
/dev/sdc1 63 625137344 312568641 7 HPFS/NTFS/exFAT
it@it:~$

When you remove usb ... .what happens? Can you select Windows loader from a F key choice or bios entry choice?

The info you posted would indicate you had a standard windows 10 install using UEFI/GPT while you apparently installed Mint in the older MBR. Not sure why you can't boot either as generally you would be able to boot either windows or Mint. Since you already have the boot repair software, the next best step would be to run it again but this time select the Create BootInfo Summary option and when it finishes, post a link to the output here as it will have enough details so that someone can suggest what to do.

On startup I can get into BIOS with F10 and other F functions but I can only boot to USB that I installed LM on. Thank You!

Thank You I will try that and post results.

what changes in the bios did you make before installing mint?

You installed LM on an external drive?

You know. I'm starting to think Linux Mint isn't a good fit for new Linux users. I think Salix/Slint + elilo with refind would have better results maybe?

I disabled secure boot and legacy and boot to usb drive

You have legacy enabled? If so disable legacy and see if windows will boot.

I installed Linux Mint from a Linux Mint USB Drive I purchased. When I installed it I followed instructions and added a parttion and a swap partition

It wont boot with legacy disabled

In that case do as Yancek suggest and post the results of the bootinfo summary

http://paste.ubuntu.com/26133401/ boot repair summary