Desktop Image Disappeared
 

My brother was messing around with my computer and by the time i got it back my desktop image had disappeared. Apparently all he did was hold down <ctrl> and <alt> and then run his hand down the f(1-12) keys. I've noticed that when I press ctrl alt 1 or ctrl alt 2 my screen goes black until i hit ctrl alt 3, which restores my desktop at a lower resolution.
I've checked the registry editor and the web tab of display properties; none of the boxes that would cause problems are checked. When I shut down my restart, however, the image appears briefly before it turns off and then again until my desktop icons appear.
I also run a linux (ubuntu) partition, but I can't see how that would have any effect...
any ideas?
Thanks!
Edit: I fixed it; turns out i just moved the file somewhere else. Put it back in my documents and everything is back to normal.