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Reset LG G5/G4/G3 Screen Passcode with Android Device Manager
 
When you signed in with Google account, then it is highly possible you already turned on Android Device Manager service. It is a remote web service to help you reset lock screen password/pattern/pin without lost any data. And the steps are quite simple to follow.
 
Step 1: Login Google Account and click here to open Android Device Manager page.
https://www.google.com/android/devicemanager
 
Step 2: Find your LG phone on the screen and turn on "Lock & Erase" feature.
 
Step 3: Follow the onscreen instructions to lock the phone.
 
Step 4: Set a temporary password for the phone.
 
Step 5: Input the password to unlock the phone.
