That may be a sign that your router is getting old/dying based on my own past experiences (that is if it's not the firmware's fault). Having to restart your router is a sign that it will happen again.
You can hard-reset your router to reset the password. Consult the manual, but usually there's a little hole you insert a paperclip into for 3-5seconds in the back next to the power cable. It's highly recommended to make sure your router firmware is up to date. It'll save you headaches in the future.
