My login no longer sees my profile

In c:\users there's a profile, we'll call it BOB:

c:\users\BOB

I've been using it since day 1 and it still has all my files.

However, when I now log into my PC with the exact same email I've always used and exact same 4 digit passcode, it no longer links up to BOB but made a brand new user called TEMP.

How do I get my windows log in that I've always used to use the c:\users\BOB information?

If it helps: when I woke up it looked like my computer got updated and I saw a weird message something like "You need to log out and back in again or you may lose files from today's session". So I logged out and in with my 4 digit code, and it no longer sees me BOB files. I restarted the computer (not shut down - but actual 'restart') and it still won't "see" the c:\user\BOB profile and uses a new c:\users\TEMP profile).

Help please!