Windows XP logs off after logging in

Hello. I've made a post on the same problem before, and it got removed due to the fact that my question was misinterpreted as me making a virus that messed up my computer. What I really meant was that I clicked on a file on my desktop (" the virus I made" or caused to happen) that looked extremely similar to the Internet browser I use. It then started to lag my computer followed by my computer actually logging out. So I apologize if anyone took it the. Wrong way ( I am only 14, so I don't even know how to create a virus let alone use it for any reason).***


Getting to the point, I cannot log into my computer because every time I get to the welcome screen, it briefly shows the desktop, then starts to log off. Ive done everything I could think of and havent lucky. Including safe modes and last good configuration (system restore does not work as i am missing a file called hp366.sys or something similar to that) etc. my computer is an HP a1637c and I've had it for around 4 years. Is there any solution? Or is it time to get a new pc setup? I've tried to find help but can't seem to get any. Thanks in advance! ( also, I didn't want to make this to long but on most occasions, I can turn on computer on, but all other things like the keyboard and mouse and monitor don't even turn on most of the time. What should I do? Thank you)