In addition to what richc46 has said you can back-up all the important e-mails and then try to re-configure your email and check if it works.
If issue persists, create a new user account and configure with the same e-mail and check if it works. Please use the following link for detailed instructions to create a new user account, ensure that the new user account is an Administrator account: User Account - Create
To back-up emails from windows mail please follow the link for detailed instructions: Windows Mail - Messages
Please post back with the results.