Q: my laptop wont allow me to log in my account but the guest account works ?

i was using my laptop normally and all of a sudden it  shut down and i turned my laptop on and the screen keeps turning grey and i couldnt use it. i restarted it and opened it on safety mode i then tried logging in my account but all it kept doing was turn grey and going back to the page. i turned logging in to the guest account and it works fine its just my account that doesnt work. what can i do to fix it        and i also have files i want >_< !