Changed my theme name without disabling it. Can't re-enable, please help Like an proper idiot I changed my theme name using .info file without disabling it first in the admin area. Now, I cannot re-enable as it does not show in the Appearance part of the administration area. 

I have already tried resetting to the default garland theme and clearing all the caches to no avail. Any idea on how I could fix this?

I am using Drupal 7 and Omega as the base theme.
You probably forgot to change folder name where theme is located.

Also see if you have changed all occurances of theme name in .info file.

It would be good also if you change name occurances in template files of that theme (template.php)