It will remove all the data ,contacts and apps that you installed
First of all, switch off your phone by holding the Power button.
After that press and hold Volume Down + Power at the same time for a few seconds.
You can release held keys when you see the Bootloader Mode.
Then use Volume Down to select "Factory reset", and press Power button to confirm this option.
Well done! The hard reset has just been performed.
Turn on the phone by using the Power button.
Afterwards go to Settings and then to Backup & reset.
Tap Reset Phone.
Choose Erase Everything if you are sure you want to clear all your data.
Select OK to confirm the whole operation.
HTC ThunderBolt Restore Factory Hard Reset Format Phone.So lets start the HTC ThunderBolt Restore Factory, HTC ThunderBolt Hard Reset.Turn Off the mobile phone for few mints.HTC ThunderBolt Remove Pattern Lock.
Hard Reset,Restart Problem,Restart Solution,Restore Factory,
Restore Hard reset will set your phone in origional factorry settings. It will remove all the data and apps that you installed. Your contacts will be removed and you have to add them again.