Two method have to unlock pattern lock
First method : Use your gmail Account for unlock pattern lock,if you have already synchronised your android device with gmail account , its very simple just need to sing in your gmail account and password for unlock pattern lock, so many people its not done.just follow the Second method and you will be reset your android device. and lock pattern will be unlock.
Second method :
1. switch off your android device.
2. Now press Volume up Button + Power Button + Home button at the same time and wait until your device is start.
( if your device doesn't have home button just hold together Volume up button + Power button keys)
3. When you see the logo screen release the power button and keep press the other buttons.
4. Now you see android system recovery tools and there is a list. Now use volume up and down key to select "Factory Reset" option Restore factory default or delete all user date depending on which is on your device.
5 . After finishing setting Factory reset completes, Now scroll down and reboot your device and wait for your device to reboot.
After Restart your phone will normal condition.
( this method deleted your old data and apps)