Windows XP system fail?

I had a Trojan virus (ms removal tool) that I was able to get rid of with malware malbytes and avg. Right after I turned my computer on whenit was fixed, I started getting pop ups saying hard drive failure and hard disk fail and then the computer cut off. When I turned it back on and everything is gone. All icons, the start menu has nothing all my files are gone. I was able to get to the control panel and do system restore and a pop up said roxio something was running and to cancel system restore so I did. Windows xp recovery keeps runnin and saying I need to buy it. I don't know if this is a virus, or a scam, or real, but I'd like to know how to fix my computer. Please help!