Re: how can i unlock my LG G2 using my computer
If you mean SIM unlock, you can't, you put the unlock code in when the phone asks for it (which is when you put in a 'foreigh' SIM).
If you mean the lock screen, bring the phone to the carrier, with photo ID showing that you own the account the phone is on. (If you don't, have the account owner with you, with his or her photo ID.) They can unlock it for you.