First lets try to reset Mail. Hopefully you still don't have anything in the "inBox" because this might blow anything in that away. However it will not blow away and Saved email folders.
1. Write down your email server settings (this is important because you are going to have to put them back in).
2. Quit Mail.
3. Navigate to the folder /YourHardDrive/Users/YourUserName/Library/Preferences/ and find the file com.apple.mail.plist . Drag that file to your Trash can (but don't delete it unless all the steps works for you, then you could throw it away).
4. Start Mail and at the prompts put you email server settings back in.
5. If the above steps work, throw the com.apple.mail.plist away. If it does not work, put the com.apple.mail.plist back into the /Users/YourUserName/Library/Preferences/ folder.
I hope this helps for you. Good Luck.