Hey. If the suggest video could not help, you will have few other options but neither of them may be free.
- If you original carrier's network lock period has elapsed, then you may be able to call them and they will be able to provide you with the code
- You can take the phone to your local mobile phone repairs center for an unlock - through the use of special equipment like the UFS
- Or you can order the unlock code from here http://sim-unlock.net/sim-lock/5/Unlock_by_code_for_LG_phones/#details