This useful video from internetteachings.com has helped me solve a problem transferring a Joomla database from one host to another.
I am working on a client’s website and was worried that I might have lost some information. The website uses the JA_Mica template with a plugin for in-content tabs; something I did has stopped me accessing pages using those tabs. This in itself is not a huge problem because we had decided to stop using the tabs anyway but I couldn’t access the content in the tabs. However I had made a backup of the site files and database about a month ago and was able to set up a duplicate of the client’s site on my Dreamhost account.
Backing up sites before working on them is essential even if you are just doing little things. The instructions on this vid for backing up and restoring Joomla databases are useful:
See also: howtojoomla.net
One problem I’m still having with the backup installation is that I’m not able to change templates for some reason.