In order to recover your Nextbook password you will need to hard reset your device. You will lose all your data unfortunately as this process will wipe your storage drive. Here are the steps you need to go through in order to get this done:
Step-1: Turn Nextbook Off
Turn of your device by pressing and holding down the Power key.
Step-2: Start The Process
Now you need to hold down the Shift key and while keeping it pressed you need to click Restart, or, if you’re using the on-screen keyboard, tap the option in order to confirm the start of the process.
On the next screen you need to choose Troubleshoot.
Once the next screen loads you need to click on the Reset your PC and then to tap the Next button.
Step-5: Now you will be able to choose between Just remove my files and Fully clean the drive. Once you decided you need to click the Reset button and let the operation start. Once done the process is over and you are good to go.