This is one of those situations where 'turn it off and turn it on again' sometimes works.
Turn off your phone. Remove the power to your router (rather just turning it off, as that often only invokes a standby mode). Wait a minute or two. Turn both back on again and, after waiting a minute or two for all the lights on your router to stabilise, try connecting again.
I certainly can't guarantee that will work but it's amazing how often it does!
If it doesn't work, remove the connection from the list of saved ones on your phone and then try connecting again from the beginning.