3Throw any other open applications off the top of the screen to close them.
Why this might help
One or more of your open applications could be reserving so much memory that there’s not enough memory left to do real work. Closing apps can free up enough memory so you can continue working.
T2. Turn your device completely off and on
NOTE If the screen is off and you can’t turn it on, or if gestures don’t work, skip to T3.Trigger a restart.
1Press and hold the power button.
2Tap Shut Down.
3To turn your device back on, press and hold the power button until the HP logo appears.
Why this might help
Shutting down your device closes all applications, frees up all memory, and reinitializes wireless services (Bluetooth® technology,
T3.Trigger a restart
1Press and hold the power button.
2While still holding down the power button, press and hold Center 
until the HP logo appears (about 15 seconds).
Why this might help
A restart may be effective if the screen is off and you can’t turn it on, or if the screen is on but doesn’t respond to taps or other gestures.
NOTE Because open applications are forced to close immediately during this kind of restart, some unsaved data may be lost.
TIP An occasional restart can be good for your device just the way a restart can be good for your computer. Every once in a while, restart your device.
T4. Top off the battery
1 Connect your USB cable to the AC charger and to your device.
2Plug the AC charger into a working electric outlet.
3Let the battery charge completely.
172 Chapter 15 : Troubleshooting