Performing a hard reset will fix common problems you are experiencing with your phone.
HTC 7 Mozart Factory Reset Instructions
With the phone powered off, hold down the Volume Up
hard-reset
ZTE Warp hard reset back to factory state
If you are experiencing problems with your ZTE Warp phone, then it may be a good idea to perform a factory hard reset to fix common problems.
Here are the steps you can take to reset it.
How To Hard Reset and Restore The Sprint HTC HERO
A master reset restores the original factory settings and will fix common issues. It will erase all downloaded content, including ringtones, contacts stored in the handset memory, etc.
Back up all necessary