Help me fix my iPod please!?

Ok, so I thought I was being so smart when I extracted all my favorite songs from my iPod. I plugged it into the computer, went into "My Computer", clicked on my iPod, and clicked on the "Music" folder. Each song was named with 4 or 5 random letters, so I renamed most of them so I could navigate through them easier. I copied and pasted the ones I wanted into the music folder on the computer and successfully burned the CD I wanted. The problem is, when I turn on my iPod to listened to my favorite songs, NONE of them will play because they are all renamed. I don't think the problem resulted from the copy and pasting, because those aren't the only songs that won't play, it's every single one that I renamed. PLEASE HELP!