It's frustrating when you want to open your phone and you forgot your lock screen pattern. Getting your phone working again is pretty simple. I know two(2) ways to unlock it if you completely forgot how to unlock it. You can either use your Google account or hard reset your device. I will show you both.
This might not work for all phones as different phones have different designs especially later models (In this tutorial, my phone is running Gingerbread).
Additionally, you can go back to where you bought your device or to a professional but that will cost money; the ones I'm showing you are free.