Like an idiot I deleted the 'Itunes Music Folder' from my computer, but I do have all the songs backed up on an external hard drive. Now in Itunes when I go to click on a song it says file unfound would you like to search for the file. I was wondering do I have to individually go through each file to allocate them or is there a way of doing all of them at once, or would it just be easier to put all the albums back on to Itunes. I'm only asking this because I have a lot of albums, nearly 2,000. Any suggestions would be appreciated thanks.

The quickest way, I'd imagine, would be to select all the songs in iTunes and then hit the delete key. That'll remove all the song entries from the iTunes music database. Then, using "Add to Library", select the directory that contains all your music. iTunes will search recursively through all the subdirectories and add any music in recognizable formats. Of course, this method will cause you to lose any play counts or ratings that may have added, but it is significantly faster than trying to relocate each song entry by hand.

don't forget to check the "copy imported songs" in the settings so it doesn't point directly at your external backup drive, but copies them back over to your hard drive.