Can't log in (most of the time)

For some reason suddenly i can't log in properly when the log in screen appears i click on a user account and it just highlights it and its really frustrating it just will not work after i keep restart and having several attempts it finally starts to load but my background appears and then nothing so having some knowledge of pc's i did ctrl alt delete and closed explorer.exe then relaunched explorer.exe and then my desktop appears.

I am not able to do everything my pc is basically running in a safemode type of thing i do believe this was left and was damage of a virus/trojan that i removed and i was wandering if anyone knows of any ways i can repair the system without having to go through all the reformatting process???