What is wrong on my laptop????????

I purchased a Toshiba laptop running Windows 7. It recently got a virus. So reset it to get rid of the virus. Now whenever I try to change my desktop wallpaper it doesn't work. When I try to set one of my saved pictures by right clicking and selecting to set it as my desktop background, nothing happens. When I do the same thing from the internet, a warning comes up saying "access denied." I'm really frustrated by this. I tried finding the solution on various websites and they all say to go to run and to type gpedit.msc. I can't find it. So then I tried to find some "group policy" or something and I couldn't find it. Can anyone help me. Is there some place in settings to change the wallpaper settings. Im ver confused and frustrated. Please help.