this took me awhile but i found a solution...
Follow these steps:
1. Open iTunes
2. Click "Account" on top menu
3. Click "purchased"
4. your songs should show up here. for some reason they were deleted from itunes but still stored, by default it displays playlist by "albums" ... select "songs" view and you should be able to scroll and see your library.
5. on very bottom right you should see small option that says "Download all" or something of that nature. it might say "download music library" go ahead and click that and it should begin importing them back to your itunes library.
SOME SONGS WERE NOT FOUND OR UNABLE TO PLAY...WHAT DO I DO?
-During this process you are able to go to a different page and your downloading will still continue. to view your library just click on the library tab on upper- middle of current page
- during this process (most likely if you downloaded music from 3rd party sources, not itunes) you may get a notification that there was a problem downloading certain songs...
for now just click ok when that warning message comes up.
1. later on just click on that song, and it should say something like iTunes was unable to locate file, it should ask you if you want to try and locate file. typically you will be able to locate the file by going to your music folder which is located in same place as "my documents" and "my pictures"
2. click on that and then there should be a folder titled "itunes music", "itunes library" or something of that nature. if your still unable to find it, it may have accidentally gotten moved to a random folder.
3. to find it, go to menu bar at bottom left of your PC and type in the search box "my pc" it should bring up a folder titled "this pc" or "my pc" click on it.
4. now without clicking on music folder, just go to search box on top right and entire title of song and hit enter, it will then search your entire PC for that file instead of searching for it folder by folder (who has time for that!) if nothing comes up, search by artist name