I just had to reset my password. I know I didnt change my password... I was online a few hours prior to this. changed my password to my old password and it let me back on psn....
I was either hacked or psn messed up.
your not alone in this...
We routinely monitor for irregular activity, and if such activity is detected, we may sometimes reset passwords of affected SEN accounts to protect consumers and their account information.
You can head to the link below to reset your password if needed.
Ex-PlayStation Network Senior Community Manager
Sony Interactive Entertainment America