Reset button

I have a sansa m240.
when I got it My computer was down so I used another computer to put songs on it. Now that my computer is working I can't seem to delete, let alone find the songs I did on the other computer, but they are still on the player and I can listen to them. I want delete them. Is there some sort of reset button or something.The computer I originally used is destroyed, so I can't go try to delete them on that computer.
Any help you can offer is very much appreciated.
Thank you
Dhabekost