Adding content to iTunes

Moved my PC to another room - Same external hard drive, connected to same PC. 80% of my songs in my library show grey letters in the "Get Info" categories but all still play. I also have NO check boxes! Any similar occurances with resolutions would be appreciated to read about. I do a lot of editing and add a lot of album art so this is important that I fix. I can download the songs/albums from my HD but it puts it in another folder, so my files are now duplicated.