The best way to safeguard your data is to create backup copies of your files. For example, you could back up your phone book from the _DAT subdirectory to either the root (C:\) directory, the RAM card (A:\) directory, or a hard or floppy disk on your desktop computer. To back it up, you have to know where to find it. You have to be able to tell the computer where you want to send it. And you have to understand file naming conventions.
Even before backing up a file you must understand the necessity of saving your work to a file as discussed in these past columns.