I have accidentally deleted my entire itunes library on my PC!

While you seemingly have lucked out in this case, this should serve as yet another lesson to set up and perform regular and proper backups of anything you feel important. As a last resort, however, Apple will, if you ask nicely and after you listen to their telling you the same thing about backup importance, let you re-download any purchased content. Admittedly that leaves all your NON-purchased content to recover, but it is nice of them to do that I suppose... Enough preaching. My catholic school upbringing is showing

That said, this should be a simple matter of pointing itunes to the library. I'm sure it's as straight-forward on the PC as the mac; in Preferences:Advanced, set the location of the music library to wherever it is (or wherever you decide to place it to suit your whims/sense of logic) on your drive.

In my case I have an alias to my real music/media files in the place where itunes likes it ("music" in your user dir) and I keep the actual files on a dedicated (big) drive. Just better for me that way in terms of backup, space-savings on the primary drive, sharing with other computers in the house/xbox360/etc... but your mileage may vary.

good luck!

just select all of your itunes content, start iTunes, and drag all of your content back into iTunes.

You will lose your play counts, your playlists, artwork and basically all metadata for the songs.

Create a new library, then Add to library and select the directory with all your music.