Big computer problem/malfunction, can anyone help?

I had a problem with a virus called msiexec.when trying to dea with it i used malware bytes anti malware ands it said i had to reboot my computer so i did then when i rebooted i long into my usual user but when i did it said desktop failed so i restarted and when into safe mode to try to fix things but i'm not sue I did any good, when i tried to log i in my usual user my computer said user profile failed, now i'm using a different user but how do i get my old user back? what should i do?