I can get to the email page but it won't show me my messages. What can I do?

There are really two main possible causes for this.
First possibility: Filter settings
Outlook and Outlook Web Access (http://mail.letu.edu) have the ability to filter which messages you are viewing. Oftentimes when messages seem to disappear, it is because the view is set to filter, so this is a good thing to check if your mails seem to be missing.
In Outlook Web Access, look on the toolbar, toward the right side, for a drop-down box labeled 'View.' You'll want to make sure that it is set to Messages. This setting will show you any and all emails in your box.

Second possibility: Web proxy interfering with Outlook web interface
Another possibility is that your browser is set up to run web traffic through a proxy for one reason or another, and that this is causing problems. If this is the case, go up to your address bar and put in:
https://mail.letu.edu
Note the 's' in there.