The two apps that you mention are in the ROM of the device. As such, it is practically impossible to corrupt them.

"Formatting" the 7135 as you say is actually called doing a "hard reset" procedure. Hold down the backlight button and press/release the reset button in the battery compartment. Keep holding the backlight button until the Palm logo shows on the screen, then release it. When you release it, the device will ask if you want to erase all (RAM) data by pressing the Up button. Press that button and all programs and data in RAM will be erased. This does not affect programs in ROM.

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Michael