First of all I must mention that I am not an expert, so the sequel is FWIW.

The screen you mentioned is the menu to login as a "user". Your computer has two user accounts, one with admin privileges, the other perhaps not, or meant to be restricted. Did you create these yourself? Has this screen been displayed before? Did you then press Return to make it disappear? If so, the computer seemed to assume the "empty" password. Which of the two user icons was highlighted?

Have you tried highlighting the other icon (click or press arrow-down) and then press Return? You might have pressed an arrow key accidentally two days ago, and now your computer keeps assuming you want to login to the other user account, which is password-protected.

If switching the highlighting does the trick and you are lucky enough to be administrator then, you can just delete the other user account if it is never used.

FWIW, as I said.