Yesterday I was on the computer and all of a sudden it started acting strange. Windows were closing, and new ones were opening without command. I restarted the computer but now nothing will show up. The background and mouse pointer are on the screen but all of the icons and even the start bar have disappeared. The computer is not mine, and I do not want to get blamed for something I did not do. Can anyone help me?

Run, Run very fast.

Now, sounds like you may have an Operating system issue. Reboot the computer and repeatedly press F8 to bring up the alternate boot screen. When it comes up, select Safe Mode with Networking. When the Welcome screen comes up, log in to the local user's account. The desktop and all icons should now show up.

IF the above process worked, you have most likely a spyware /malware infection that you need to get rid of. Because you're already in safe mode, now's the time to do it. Check out the following links:

Spyware and Virus Infections - Helljack6.com (http://www.helljack6.com/infections.html)
Using Spybot - Helljack6.com (http://www.helljack6.com/spybot.html)
Using Malwarebytes - Helljack6.com (http://www.helljack6.com/bytes.html)

When completely done scanning, Click Start, Run and in the run box, type CMD. At the command prompt, type CHKDSK /f /r

You'll be prompted that the drive cannot be locked and would you like to schedule chkdsk at next system reboot, say yes then at the prompt again type exit. Now reboot the computer. When the computer reboots, chkdsk is going to run and fix any problems it finds. An alternative method if you have a copy of the Operating System Disk to here - Using the Recovery Console - Helljack6.com (http://www.helljack6.com/console.html)