[SOLVED] Computer can no longer see USB as boot option

[chico1st]

My USB harddrive with windows 10 that I book into, crashed last night and now my computer doesn't recognize it on boot.

I can still however use it as a USB drive when I'm not booting into it.

The way I access it (instead of the inbuilt hard drive) is via a temporary startup menu on my Lenovo and the USB drive isn't even listed there, so I don't think it's some simple MOBO startup sequencing.

I'm not sure how to repair it since I can't even select the drive during power on to trigger it into a safe/repair mode.
Maybe there needs to be some special file on the drive so that windows can see it?

Help please :O and Many thanks!

 

[Hellfire13]

First, get into BIOS and give boot device priority to removable drive. If it still boots to your default drive, remove the default drive keeping the same priority and see what error message you get on startup. Probably your external boot corrupted.