Ok, back to the question. Your machine did a hard reset. There are only a couple of things that could have happened: Total battery failure. Spurious button pressing.
The spurious button pressing is unlikely, but possible. However, check this
thread for another potential reason for a hard reset.
The battery failure is more likely. That failure could be because it was dislodged somehow, totally discharged somehow, or simply that the Axim saw an interruption in the power supply from that battery. In addition, the backup battery failed to take over and preserve memory. That backup battery problem could be because the battery is a little loose in the pocket in which it sits and lost contact with the little fingers at the bottom, or that it really is dead. Since you didn't report any messages about batteries, I will assume the first problem. Plug in the Axim to the power supply but leave it turned off. Open and remove the backup battery, clean it carefully with some alcohol to get all grease from fingerprints off of it and inspect the little fingers at the bottom of the pocket to make sure they are up enough to make contact. Now put the battery back in the pocket. If it was loose before, you might put a very thin padding on top of the battery before you put the cover back on. Non conducting foam, or even a square of paper folded over to make a small pad would do. Just enough to press the battery in nice and snug. Now put the cover back on the backup battery.
Check the main battery for being securlely locked in place. It may have a little play in it, but not enough to dislodge it. With the Ax still plugged in you can remove the main battery and check the contacts to make sure they are clean.
Hope this helped.