We've heard similar issues hundreds of times now and I don't believe that we have any definitive solution for you.
It usually involves an issue with your keyboard (input device).
If it is wireless, then you may have to substitute a USB wired keyboard temporarily to get you over the hump.
More often it involves a problem with the language / region / keyboard layout settings, so.....
IF, you see anything on your screen that offers something regarding "Language" click it and see if that produces an optional choice.
Additionally double check and confirm that .....
The account name you are using is the one you expect to use.
The password is being entered exactly as you are typing it by using the "Eye" icon in the password text box.
Try using the On Screen Keyboard from the Ease of Access Icon on the sign-in screen and see if that produces any relief.
