This question already has an answer here:

Seen many questions on this matter, but as I can not access CTRL-ALT-F1/2 I'm stuck into this loop. It keeps asking for password, clean orpheants and back to login. As I can NOT open any manager/control window it's somekind of strange behavior. I can NOT login as myself OR as guest. :-(

marked as duplicate by Android Dev, Pilot6, Zanna, amc, Eric Carvalho Nov 15 '16 at 17:42

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

Browse other questions tagged or ask your own question.