My keyboard does not type the right letters

I don't know if this information will help, but I had the exact same problem and after a lot of tinkering, it finally worked:

At the startup screen, when prompted for the password, my keyboard was completely blocked, it validated my input, served as a back button...

I went into the accessibility options to enable the on-screen keyboard.
I tried various attempts, like those mentioned above, to no avail.

Then I clicked on Alt, then Shift, then FN, and started typing my password using the mouse, and it worked.

After logging in, the problem had disappeared!

With that, I hope this will be useful to some, and good luck.