if it was a prank web site did it change the windows desktop image to the web page photo?? right click on the desktop and under windows 7/8 click on personalize and look to see what the desktop image was set. if it was a virus or malware use malware bytes and hitman pro see if it can find and remove it. also use msconfig look under the startup tab see what loaded. a lot of virus will load a fake program that launches from startup. also look under add/remove programs for programs that were installed when the issue started.