If using a mail app delete the email account in the app and set it up again. If it happens to be AOL mail they changed things for 3rd party apps so you had to delete and reset up the account in the app last month or move to the AOL email app. I reset my AOL account in my Samsung mail app when I got the email about this last month and have had no problems.
We are sorry to read that you are having issues with your email, we'll be glad to help out. Are you able to access that account with your browser or with a computer? Have you tried resetting your password?