If you don't remember the Gmail information and it is "pattern" locked out...then you can do a "button" factory reset. Unfortunately it will erase everything on the phone but leave everything on the Micro SD card untouched. The steps are:
Hard reset on LG Optimus:
1. Turn the power off. If the Optimus is frozen, pull the battery out and reinsert it
2. Hold volume down, home, and power buttons until the reset screen appears
3. Scroll down to wipe data/factory reset (using volume down) and press menu
4. There will be a lot of no's, and one yes. Highlight yes and press menu
In the future, if you are ever able to remember at least the Gmail address, you can go on a computer to Gmail.com and click I forgot my password, enter your security answer and then get access again...Then set up that Gmail address on the phone and it is possible you can get your contacts back. If you have any more trouble or complications, please reply and let me know!. Good luck!