If you're still running the original virgin Sharp ROM you can follow the following procedure to return your 6000 to its original state. If you're running a different ROM, then lets hope that someone else provides an answer, as I've nary a clue.
According to the Sharp SL-6000L/SL-6000N personal mobile tool Start-up Guide, pages 87 & 88...
1. turn the Zaurus off and make sure the screen has gone blank.
2. attach the AC adapter, making sure the charge light comes on.
3. press the reset switch.
4. press the On/Off key while holding the OK key to display the Maintenance menu.
5. select Format, which erases all data in the Zaurus Internal Flash memory and then reformats the memory. Data or settings entered after purchase or software you have added will be deleted. Application updates and the contents of the Zaurus system will not be erased.
