If you have a problem with the PlayStation Vita and need to access Recovery Mode, you will need to do the following:
* Ensure that the Vita console is turned off
* Press the PS button, Power button and Right Shoulder Button at the same time and hold for couple of seconds.
* You will now have a menu with the following options:
1) Restart the PS Vita System
2) Rebuild Database
3) Format Memory Card
4) Restore the PS Vita System
5) Update System Software
(Please note: you must use the PS Vita system's buttons to operate this menu).
credit to RabidWalker psn