How to Get My iTunes Music Back
iTunes stores your media library (including all of your songs, videos, audio books, etc.) in one file somewhere on your computer. If you open iTunes and find all of your songs have disappeared, it is because iTunes cannot locate this important file. Once you yourself locate this file in its new location, you can then use it to get all of your music back into iTunes.
Type "iTunes Library" into the "Search" box. This will find your misplaced iTunes library database file on your computer.
Right click on the iTunes Library file and select "Open" to open it in Windows Explorer. Make a note of the directory where the file is currently located. You will need to know this in a few seconds.
Click "Choose Library" from the box that appears on screen indicating that iTunes can no longer find your iTunes Library. Navigate to the directory you located earlier (where your iTunes Library file was moved to) and double click on it. This will tell iTunes that you have selected this particular library file, which will restore all of your music into iTunes.