I add songs from my computer to my Sansa sandisk 2GB, they don't show up if I want to listen to them

I’ve added some new files to my Sandisk player. They are the same file types as the ones that I already have on it. For some reason these ones don’t show up in the music list if I want to listen to them. They are the exact same file type. I don’t know what to do to make them appear. Thanks.

We need tons more info if we are gonna be able to help you. What kind of Files are you  using? (I need File extentions) How are you trying to transfer the songs? How did you get the songs?

This will get us started.