what shuld i do?
Check first if you meet the minimum system requirement for your Sansa Clip; ie. Windows Media Player 10 or 11 on a Windows XP or Vista computer. If you not then you may need to upgrade your WMP from the Microsoft Website.
You can also try switching the hold button to lock(downwards where the orange is showing), then hold down center button while you plug it in to your computer.
You can try the other troubleshooting steps recommended on this site if still the player is not recognized.