Hard resetting / factory resetting your phone will solve the following issues:
1. If you forgot your pattern lock
2. If you forgot your gmail account
3. If you forgot your password
4. Apps that automatically force closing
5. Stuck in MyPhone Logo (sometimes does not work if the firmware is totally damage)
NOTE: Performing hard reset will erase your data.
To hard reset:
1. Turn off your phone
2. Press and Hold Volume Down + VOLUME UP +Power Button simultaneously, a selection will appear.
3.Press Volume UP to enter Android System Recovery
4. An Android with exclamation mark will appear, Press POWER Button to reveal the Android System Recovery
5. Select wipe / factory reset, press Volume rocker to navigate and press the Menu Capacitive key to confirm your selection.
6. Reboot your phone.
Note: If performing hard reset did not succeed, you need to wipe the cache first in the android system recovery before performing wipe / factory reset.
I hope this tutorial helps you.. If you have any question just drop a comment.