El Capitan suddenly has 3 people in a circle @ startup and my password no longer works

Suddenly i am locked out of my mac. I never had any firewhat'sit security setup there isn't even a guest mode and no passwords work + it is asking for a "Name" . . .what is frigging going on apple what have you guys done? It was running el Capitan latest version then i suddenly had a circle with slash thru it - did command opt R ran disk utility it reported all was good but now i am @ this dead end . . . anybody have any ideas ? Mahalo