I've found these hard reset instructions maybe they will help:
How to perform a hard reset on a Treo 650:
WARNING: This will erase all your data!
1. Open the battery cover and locate the Reset button.
2. Press and hold the reset button with the tip of your stylus.
3. Press and hold the power button (on front).
4. Release reset button, while still holding down the power button. The device will begin to power up. Continue to hold down the power button through the PalmOne progress bar screen.
5. Release the power button once the screen has the circular Palm Powered logo.
6. A confirmation message will appear, asking you if you REALLY want to delete everything and reset your device to factory settings. Press the UP button for a hard reset. Press any other button for a soft reset.
7. Sync your device to restore data. I recommend looking at your conduit settings before performing your initial sync... you may need to select "Desktop overwrites handheld" on some third-party conduits.
I'm sure you know how to hard reset, but maybe you pressed something by accident. Wish i could get it working for you
