ipad says wifi password incorrect

If your iPad reportedly reports an incorrect WiFi Password, assuming that the password that you have entered is both correct and accepted by other devices, then your WiFi Router may be the source of the problem. This problem is often resolved by simply restarting the Router.

To restart you home router, disconnect power - then wait at least 30 seconds before restarting. When you router has rebooted (which may take several minutes), force-restart your iPad:

• On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
• On an iPad with Face ID: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.

Look at the label on your router for the password (if it hasn't been changed by you).