Here's how to export an .sql file containing all your db contents:
1. Login to phpmyadmin from your control panel account
2. Click on your db name in the left hand column
3. Click the Export tab at the top of the page.
4. Leaving all settings alone on the next page, just click the GO button in the lower right corner.
5. Allow the database a few moments to complete your request. The next screen is an SQL export of all database contents. Simply copy the contents of this window and paste it into a TEXT editor (such as bbedit or the free TextWrangler app. DO NOT USE A WORD PROCESSOR AS THIS WILL CAUSE THE EXPORTED DATA TO BE UNUSABLE.