Sounds like you are remotely hosted and have only PHPMyAdmin as a backended tool ... ie, NO ssh access. That correct?
If so, where is it hosted? Hosting providers do have FAQ's/KB's/support areas for their customers. In this case, you might have to contact hosting provider help desk and inquire.
Two questions ...
1. did you do an SQL dump of the DB for the original DB? .... from what you have written, doesn't sound like it. Shame on you! :\
2. Have you checked settings for PhpMyAdmin to see what DB server its pointed to? When you moved the Moodle code/data directory to another domain, am assuming the PhpMyAdmin you're using is still pointed to the DB's used for the old domain. You didn't drop the database did you?
Here again ... you might have to contact hosting provider.
'spirit of sharing;, Ken