My sansa when its connected to my computer comes on works syncs and everything so as i disconnect it from my computer it' s dead and wont turn on
1) You have a dead battery because the battery is no good.
2) You have a dead battery because your Sansa is no longer charging the battery.
3) You have a dead battery because you didn't leave your Sansa tethered long enough to charge it up.
When you have the Sansa c250 tethered to the computer, you should see a tiny yellow lightning bolt flashing, and a battery icon that shows the amount of charge on the battery.
If you see the lightning bolt, but the battery does not charge after being tethered to a working computer or charger for 24 hours, you may need a new battery. You can get one on Amazon.com. Here's a link:
If you see the lightning bolt, and the battery charges after 24 hours, AND your player works when unplugged--Problem solved! You just need to let it charge for a longer time.
If you do not see the lightning bolt when the player is tethered, and the battery indicator shows "empty," It's likely that the internal plug to your Sansa c250 has broken. Your Sansa is no longer able to charge the battery.
If you happen to be an electrical engineer, or otherwise have a shop full of electronics equipment (including signal injector, volt-ohm meter, needle-tip soldering iron, and stereo magnifying goggles with work lamps) you may be able to fix it yourself. Otherwise, forget it-- your Sansa is dead.
If it's still under warranty, try to get it replaced. Failing that, it's time to get a new MP3 player.
Hope that helps! Please post a message to let others know what happened to your Sansa player.
SanDisk Sansa ...
on Nov 26, 2011