Do you still have tracks in iTunes? I use an old iTunes and I have changed how it behaves in this kind of thing relative to non-altered iTunes.
If there are still tracks in iTunes try playing a track in iTunes. Will it play? Right click on a track in iTunes > Reveal In finder. Where is the file in the folder structure on your computer? In the iTunes folder or in the Trash? It is possible that dragging the files to the trash from the iTunes window simply put copies of all the files in the trash. You don't have to worry about them.
If there are no tracks in iTunes then I guess it literally deleted them from iTunes and moved all the media tracks to your trash. Right now they are still taking up space on your drive until you empty the trash. I am not sure what the 13041 message means.
I guess two courses of action. One is to empty the Trash and restore the iTunes library from your backup. The easiest way to do this if you are confident your backup is reasonably up to date and complete is to copy the whole iTunes folder from the backup over the one in your Music folder (empty the Trash first so there's room on your drive). Start iTunes and it should use the old library. Everything in a "normal" iTunes is inside that iTunes folder (as per all those links I posted earlier).
If you do not feel comfortable doing this then let me know and we can work on it some more (but I have to help with supper for a while 😉 ). My main concern is if you had a last minute addition to your library post pst backup and it's only in the Trash right now.
By the way, is this really on a G4 as indicated in your profile?