Restore playlists with moved files

Hello,

My computer was almost full and i decided to put my iTunes Folder in external hard drive.

After that, i erase from my documents and emptied from my waste.

Then i add back from my external HD.

But the most important thing in my iTunes is my playlist, that i always keep very organized!! But now they are unable to play the songs because is no more in the same location!!!

Please, tell me that is a way to restore my playlist that i had so much work to build.

Somebody can help me??

Thanks so much.