If you've failed to unlock your device using this method, after five attempts you should receive the option to either tap either "try again" or "next". If you hit "next", you will be given two options for unlocking - either answer a security question or use your Google account details. If you haven't set a security question, you can use your Google account details to sign in, after which the device will give you an opportunity to create a new locking pattern.
If neither of these methods work, there is another option that will involve a factory data reset. (Note: this will erase all of your data) Start by switching off the device. Then push and hold the volume up button, the power button, and the home button, all at the same time. When you see the manufacturer logo, let go of the power button but keep holding in the other two. Your screen should then show an "Android system recovery" menu. Use the volume keys to navigate this menu, and select the "factory data reset" option. Hit "yes", and after the process is complete, you will be returned to the same menu. From there, select the "reboot" option, and your device should start up again, requiring no pattern to unlock it.
