This is how to hard reset your china phone which is used MT65xx Chipset, resetting this handset is very useful when you forgot your pattern password, feel slow doing something in your phone, restoring your configuration to normal, repair your system file, and anything else.
How to do hard reset :
1. Connect the cable from the computer while holding down the "-" - the volume below the sidebar.
2. Turn on your phone
3. Phone will boot in FACTORY MODE
4. Select the Clear Flash using the same button "-"
5. Confirmed by pressing the button "Menu" button on the left touch of a round button.
Some information that can help you for this device
- Entering the engineering menu by dial *#*#3646633#*#*
Hope this article could help you for something :)
source : Here