Power cut off

I was in itunes playing music and the power totally cut off. When I cut the power back on and log back in and came back to itune a lot of my music that I had accumulated are gone. I had over 2,000 songs, now I only have 170 and 3 sources that I had on the on the left panel disappeared also. Can I retrive this music back? I paid money for these songs from the music store.