MyBB Community Forums

You'll need to transfer all your files and database then, this tutorial should help - http://community.mybb.com/thread-27771.html

^Yes, this was the thing that rendered my forum useless!

Just do a home dir backup and a backup of all your db's in cPanel.
Then go to your new host and upload these backups through their cPanel.

Here's a beta guide made by me after i changed my domain: http://nayarweb.com/forums/thread-164.html

If you have a download of your files and database there's no way you can lose anything, because you'd have downloaded it... what exactly happened last time??