Motorola T720c Troubleshooting
Lint and/or dust may have collected under the screen.
The seals around the screen on this phone are not as effective as some newer models. Removing the phone's faceplate will expose the screen so that it can be cleaned. Step-by-step instructions can be found here.
Debris has collected under the buttons or between the keypad and the phone's frame.
Seals surrounding the keypad are not adequate to consistently keep lint, dust and other small particles from accumulating underneath and around the phone's buttons. Removing the back of the phone will expose the keypad, which can be extracted and cleaned, restoring the functionality of the buttons. For a step-by-step guide and photos, refer to this page.
Your phone's antenna cannot be retracted from or reinserted into its holster.
If the antenna has become warped or bent, it cannot be properly housed in the base of the phone and may warrant replacement. To remove the antenna for inspection or to replace, unscrew it from the body of the phone and inspect it for possible damage. These steps and a photographic guide can be found here.
The phone needs to be reset -- phone battery reset
Occasional software malfunctions (such as the phone's screen or applications freezing) can generally be remedied with a battery reset -- removing and reinserting the phone battery.