Hi,Thank you for using Just Answer my name is ***** ***** I will help with your question.I am afraid you might need to reset you phone to factory settings to reset the resolution back. This will cause you to lose all your data and settings.I have something I would like you to try before we look at restting the phone. Do you have the samung Kies software on a computer. I would suggest plugging the phone into a computer you might be able to unlock the phone using the computer and then reset the resolution instead of having to rest the phone back to factory settings.
Thanks for that.Have reset the phone to factory settings.Fun begins now re-installing.