In case you have forgotten the account or pattern you can solve this using a different method.
Please install Android SDK tools then connect the phone to the computer. Start a Command Prompt and type: adb shell. Input the next command: rm /data/system/gesture.key then restart your phone. Once the phone restarts, connect it back to the computer and use the shell again, you will need to type the following commands now:
adb shell
cd /data/data/com.android.providers.settings/databases
sqlite3 settings.db
update system set value=0 where name=’lock_pattern_autolock’;
update system set value=0 where name=’lockscreen.lockedoutpermanently’;
.quit
After this, input any pattern and the phone will be unlocked.