When I open my Mail app on my Android phone, it now asks me to choose a provider.

[AC Question]

When I do that it brings up an add account screen, but it tells me that account already exists. It won't receive any emails or let me open my account. I can't get past the add account screen.

 

[Rukbat]

Go to Settings/More/Accounts, to the email accounts, and delete the account. Restart the phone, go back there and add the account as a new email account (new to the phone, not new as in create an account on the server).

If that doesn't work, try going to the webmail page for your account, or accessing it with the email program on your PC.

If that still doesn't work, contact your email provider.