I open my computer and it says in summary, autorepair couldn't repair your pc find the reason why at "C:\WINDOWS\System32\Logfiles\Srt\SrtTrail.txt"

I look inside and I find that the error it is talking about is 0x490.
Root cause found: boot manager failed to find OS loader.

I have loads of passwords and other information baked into the windows install itself which I would very much like to keep intact so I could sort them for a later date when I do a clean install on this machine.

I also have files which I will need for a court process on that machine so I would also like to keep it intact since I would much rather be sure I backed up everything when windows if fixed than booting up with a linux usb.

I have tried the usual fixboot command and it spewed out "access denied".