Afraid my files didn't save

Hello, I hope someone can help me. I only bought a WD Passport Essential as I needed to restall my system. I had easily over a hundred songs (proably close to 200 or more) saved on my computer and I wanted to save them in addtion to my pictures, documents and photos.

I could swear that before reinstalling I checked the hard drive and saw all the songs were backed up. When I retrieved my files-with the exception of maybe 10 songs they did not download, and I now don’t see the songs on the hard drive. I afraid that I have lost all these songs. The songs were in Real Player format, as were my videos; the videos all saved and were retreived so I’m quite perplexed as to what happened to my songs. Does anyone have any idea what may have happened were could I find the songs on the My Passport? Thank you in advance.