Laptop problems? it keeps restarting then shutting back down?

I have a laptop and its really been working perfectly for years , until I downloaded iTunes and started putting music on my iPod. I think it got a virus.(I'm 15) my parents spend A LOT of money on me and I felt like it would be wrong to ask them to pay to get rid of a virus that was MY fault. so my mama saw me doing my online classes in the guest room and she said she would buy me the anti virus. we downloaded McAfee. and everything was fine. but my cousin (playfully) punched me and I jumped up , causing my laptop to close. after I opened it , it was saying that it could not start then it was trying to find out why and after 15 minutes it just Said it could not find the problem.. then shut down and restarted it keeps doing that. I'm sorry this is so long but I really need help. Idk what to do