WARNING! Master resetting your phone will result in the deletion of all personal data located on the internal memory. This includes media files, downloaded content, contacts, apps etc. Furthermore, all settings will be restored to factory values.

NOTE: Before you master reset your phone you can visit this thread for a guide on how to back up data. For instructions on restoring data, visit this thread.

Factory Reset via Settings:

1. Open the apps drawer
2. Launch “Settings”
3. Scroll to “Personal” and tap “Backup and reset”
4. Optionally, enable or disable “Restore” and “Back up my data”
5. Tap “Factory data reset” > “Reset device”
6. In case your phone is lock-screen protected, enter the PIN / password / pattern to proceed
7. Tap “Continue” > “Delete all”

Factory Reset via Recovery:

NOTE: In case you are unable to master reset the Galaxy J3 via settings, you can try factory resetting the device from the recovery menu. Recovery can be accessed by performing a combination of button presses, as follows:

1. Turn off the phone if necessary
2. Press and hold “Power”, “Volume Up” and “Home” simultaneously
3. At the “Samsung” logo, release “Power”
4. When the “Android” logo appears, release “Home” and “Volume Up" as well
5. You should now have access to the “Android system recovery” menu
6. From the menu, press “Volume down” repeatedly to highlight “Wipe data / factory reset”
7. Press “Power” to select the highlighted option
8. Press “Volume down” to highlight “Yes – delete all user data”
9. Press “Power”
10. Once the phone is reset, you will be prompted to “Reboot system now”. Press “Power” to confirm

Check for OS Updates:

NOTE: After resetting your phone, it’s recommended that you check if new software updates are available for download. To do this:

1. Tap “Apps” on the home screen
2. Open “Settings”
3. Tap “About device” under “System”
4. Verify if a new OS version is available, and if necessary, follow the on-screen prompts to download and install it