Windows 7 black background

hello admin,mods,members,and guest....I have window 7 , one night I downloaded songs from website like youtube,reverbnation,etc...all them (mp3) put them into the window media player , had like over 700 songs, and then I remember shutting it down that night and next morning right afternoon when I open it , everything in my computer was deleted and the wallpaper was black , is it virus? I think it is, also I have scan found nothing ,also check to see if it is genuine or not, it is genuine, I have done everything and there seem to be no problem but when I change my background , and restart my com,the background turn back to black(more like is black), please how to fix this problem? thanks -ngaihboy 2
P.S plz help me and be patience as I am just merely a High SchooL student that have no idea (not expert or anything) on computer!! thanks :)
 
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