This is just a guess before it froze did you set a sleep timer? If you left it on with no sleep timer the image might have permanently burned into the screen
Simple video on how to hard reset Nextbook Android Tablet. Power off device, select volume up and then power, hold power for 5-7 seconds and let go without releasing volume up. When u get the android menu scroll down to wipe data navigating with the volume buttons and then to wipe data.20 Aug 2013
Go to your search bar and ask the question it will send HELP NUMBER +1 833 272 0777you to a site where you should be able to find it and be able to download it.
Are these bluetooth headphones? Do they connect to other devices?
You probably need the DRIVER for the headphones (from that manufacturer's website) to be loaded on to the Nextbook.