Camera isn't handing to stop responding to your mobile. In this case all the data of your phone will be deleted. First switch off your mobile. Then unplug the battery and insert the SIM card and memory card. Install the battery but do not turn on the mobile. Then press your mobile's " Volume up + Home Key ( if any) + Power Button" together. A DOS -like screen or Recovery screen will appear. There will be several options on this screen. There will also be something like " wipe data / factory reset" . With Volume Key you can move the cursor up and down. Remove the cursor and click on " wipe data / factory reset" option. Then click yes . Then the mobile will do something by itself. When that is done, the recovery screen will come again. Now click on " Reboot System Now" from there . Then your mobile will be restarted. Diameter is the end of your work. Once the mobile is on, you need to make some settings (Language Select , Email , Time , Date, etc.). The work is done. Now your mobile is brand new.