Recover data in my PDA (mobile device)

I use a PDA (mobile device) to store my contact, calendar, notes and other important information.

The internal battery of my PDA died. I lost the data on my PDA.

I was able to retrieve the data from my desktop computer, as I synchronised them regularly.

I just learned, after losing the data, that I could also backup the data on the PDA into the storage card. This would have also allowed me to recover the data. I shall do it regulaly as well.