My Mail on my mac doesn't working well

Question

Why my Mail on my macbook pro doesn't working well, I couldn't see the content of my e-mail messages. how do I do? I tried to reinstall my Mail, and I couldn't fix it. Please help me

Answer 1

These fixes have helped others, depending on the situation.
Have an up-to-date Time Machine or other backup before attempting any major software updates or rebuilds.
For more about backups:
Time Machine Basics: http://support.apple.com/kb/ht1427
Most commonly used backup methods: 
https://discussions.apple.com/docs/DOC-3045
Methodology to protect your data.  Backups vs. Archives.  Long-term data protection:
https://discussions.apple.com/docs/DOC-6031
Make sure your software is up to date.
Apple > Software Update...
A general repair to fix odd behaviors in Mail is  Mailbox > Rebuild.
Try booting in Safe Mode.
          Boot and when you hear the bong hold down the Shift key.
          It will boot slowly.  Be patient.
          Login the the user account.
          Restart.
Another fix:
Shut down Mail.
Open the Finder. From the Finder menu bar click Go > Go to Folder
Copy and paste the following
~/Library/Mail/V2/MailData/
Click Go.
Move all "Envelope" files to your desktop.
Restart Mail and let it convert/reindex your mailboxes.
If this worked, Trash the Envelope files file that are on your desktop,
if not shut down Mail and put them back.
Another fix:
Shut down Mail.
Open the Finder. From the Finder menu bar click Go > Go to Folder
Copy and paste the following:
~/Library/Containers/com.apple.mail/Data/Library/Caches/com.apple.mail/Cache.db
Click Go.
Move the Cache.db file to the Trash.
Restart your Mac and try Mail.
Another fix:
Open the Finder. From the Finder menu bar click Go > Go to Folder
Copy and paste the following
~/Library/Mail/V2/MailData/
Click Go.
Move all the Accounts.plist to your desktop.
Restart Mail.
If this worked, Trash the Accounts.plist file that is on your desktop,
If not shut down Mail and put it back.
You can try restoring mail from a Time Machine backup.
Hold down the Option key and in the Finder Go > Library
Enter Time Machine.
Select a date and time from when Mail was working.
Restore Mail.