An accidentally deleted iTunes playlist is restorable if it was previously backed up, as the program stores a backup of your iTunes library in the program's folder. These backups preserve your song and video's play count, playlists, ratings and ID3 tags. In order to restore a deleted playlist you must restore the entire library, which is imported into iTunes and overwrites the existing library. Once the previous library is restored, the playlists are located in the side menu of iTunes in the same condition as when they were initially saved.
Open your "Music" folder and double-click the "iTunes" folder. For Macintosh computers the Music folder is located in Finder in "/Users/(User Name)/Music," or in "\Users(User Name)\My Music" for PC users.
Drag and drop the "iTunes Music Library.xml" file in the iTunes folder to your desktop.
Delete the "iTunes Library" or "iTunes Library.itl" from the iTunes folder.
Click "File" on the iTunes menu. Click "Library" and "Import Playlist."
Click the iTunes Library file in the Open window, and click "Choose" or "Open" to import it.