Dont panic all u need to do is go to advanced (top of the itunes page, right across from file) and go down and click "Get Album Artwork". There u got back ur album art., U can also do this individually by right clicking a song and clicking "Get Album Artwork" (this proccess is free)
P.S all albums may not be labeled correctly and u may not get every album artwork but u will be able to get most.
