I have purchased and downloaded over 300 songs. Lately when trying to play from my windows 7 computer, the songs displays !. I have looked on line, done all I could but the computer still can't locate my files. Can I delete and re-download

Please help. I cannot play my songs because of ! which is located in front of my songs. I've been online support and it does not help me. My computer still cannot locate my original files. I have windows 7 program and ITunes used to play real good.

Would it be much easier to delete all of the music in my I tunes library and start all over again by re-downloading from the I Tunes store?

Really frustrated with I Tunes on my computer.