There is a lack of specifics in your post. You have no idea what you did? Is it asking for a PIN or password? That doesn't just happen by accident. If you really don't have a clue you may need to do a factory reset and start over.
Hello Mamagal, congratulations on your Nextbook 7 and welcome to the forum. Nice to have you as a member of Android Tablets. I'm moving your thread to the E Fun Tablets section for you, where more people with that tablet are likely to join the discussion and try to help you. Good luck!