so this is just off the tip of my head; it could be that your computer has been infected with a virus, you can try Malwarebyte's Antimalware, Super AntiSpyware
Or take a read of (post 4 of Grif's advice
I have a Lenovo Desktop, running windows XP. My computer lets me access the internet, but I cannot open any programs such as looking at my pics, or listening my music. Can you tell me what may be the problem?