susie, I'm having a think about this. It doesn't help you, but I do like a puzzle!
I know it sounds obvious, and I'm probably teaching my granny to suck eggs, but passwords and email addresses are usually case sensitive, have you checked this?
I'm only saying this because I have a new keyboard and can no longer tell if CAPS lock is on or off , I used to have a green light which alerted me. It's driving me crazy, so I usually end up opening a Word doc and typing on that first, as I too am having problems with my passwords!
Some sites, such asPAYPAL and Ebay do force a password change occasionally to protect you.
One of the solutions suggested for passwords not being accepted is to sign out of wifi, reboot your device and log back into wifi.
Before you log out of wifi, ensure you know your Wifi password to enable you to log back in again.