UNLOCK YOUR ANDROID PHONE

Unlock your Android device using Android Device Manager (ADM)

the following method only applies to devices that have Android Device Manager enabled.

      On a computer or other mobile phone, visit: google.com/android/devicemanager

1. Sign in using your Google login details that you also used on your locked phone.
2. In the ADM interface, select the device you need to unlock (if it isn’t already selected).
3. Select ‘Lock’
4. In the appearing window, enter a temporary password. You don’t have to enter a recovery message. Now click ‘Lock’ again.
5. If it was successful, you should see a confirmation below the box with the buttons Ring, Lock and Erase.
6. On your phone you should now see a password field in which you should enter the temporary password. This should unlock your phone.
7. Now, before you go on with your life, go to your phone’s lock screen settings and disable the temporary password.
8. That’s it! 

Unlock your Android lock screen pattern with your Google Login (only Android 4.4 and below)

If you haven’t updated your firmware to Android Lollipop (5.0), then there’s a faster way to unlock a lock screen pattern.

1. Enter a wrong lock screen pattern five times (shouldn’t be hard if you don’t remember the correct one)
2. Select ‘Forgot Pattern’
3. Now you should be able to enter a backup PIN or your Google account login.
4. Enter either your backup PIN or your Google login.
5. Your phone should now be unlocked.

Erase your phone (and lock screen) using Android Device Manager

If all the methods above didn’t work out, you need to move on to more drastic measures. In case Android Device Manager is enabled on your phone and unlocking it didn’t work, you can use it to erase all data by selecting the Erase button. Be aware that this will delete all apps, settings and other data on your phone. The good thing is, once the erasing process is done, you can use your phone again (after setting everything up).

Reset your phone to factory settings

If Android Device Manager doesn’t work at all for you, your last resort is to make a factory reset on your device. On Nexus devices, this can be done in recovery mode, for example. Below, we take you through the reset process that work with Nexus devices. If you own a different Android phone, check out this site and look for your manufacturer’s support page.

How to perform a factory reset on your Nexus using recovery mode:

Important note: If your Nexus device is running Android 5.1 or higher, you’re required to enter a Google username and password associated with your device after the factory reset process finishes. This is a security measure to make sure that no stranger is resetting your phone or tablet. If you fail to enter that data, the phone won’t be usable anymore. Really make sure you know your Google username and password.
No matter what version of Android you’re running, you need to have an internet connection and if you just changed your Google account password, you need to wait at least 72 hours before starting the reset process.

1. Turn off your device.
2. Press the volume down AND power button and keep pressing them. Your device will start up and boot into the boot-loader (you should see “Start” and an Android lying on its back).
3. Press the volume down button to go through the different options until you see “Recovery Mode” (pressing volume down twice). Now press the power button to enter recovery mode.
4. You should see an Android on its back and a red exclamation mark.
5. Press and hold the power button, then press and release the volume up button. Now you should see “Android Recovery” written on the top together with some options.
6. By pressing the volume down button, go down the options until “Wipe data/factory reset” is selected. Press the power button to select this option.
7. Using the volume down button again, go down until “Yes – erase all user data” is selected. Make sure you read through the notes above and then, finally, press the power button to start the reset process.
8. Once the process is done, press the power button to select the reboot option. Your device will now reboot and start the initial setup process of your device. That’s it! All you need to do now is to set up everything and restore your data.

You can also check out Google’s official page and follow the instructions there.
As already mentioned earlier, be aware that resetting or erasing your device will delete all data like apps, settings, videos and pictures.