The screen unlock pattern allows you to secure the access your Android phone. If you no longer remember the unlock pattern of your device you can always sign-in with your Google account. But how will you proceed when you phone is not connected to the internet?
Reset to factory settings
The only solution is to (hard) reset your Android smartphone to factory settings. The procedure may differ from one phone model to another. Be informed that you might loose any data that are not synchronized :
LG Optimus L: In order to proceed to the hard reset of the phone, you need to witch it off, then press 3 butons at the same time : Vol Down + Home + Power . The phone will vibrate and switch on, you can then release the buttons.