My Sansa automatically turns off when its turned on

You could try resetting the player by holding the power slider in the up position for at least 30 seconds. If that doesn’t help, then I guess the next step to try would be to format the player using the player’s menu)settings, system settings, format) which deletes all the songs on the player, then copy the songs to the player again. Before copying the songs to the player again, you should run chkdsk/r on them to find corrupted files.