I need my computer back to factory settings

Hello,

I have a Dell Latitude d531. I got it from my college and it is mine. They said I had to repair it myself. I can't do anything. I can surf the web, open up a cd to run something. I need to set it back to factory settings. I can't open up desktop programs. I tried to run a virus scan and it won't work. I don't have the funds to go and get it repaired. Any suggestions would be greatly appreciated. It won't even let me do a factory restore the normal way. PLEASE HELP ME. Thanks so much.