Blank wp-admin page?

You’ve probably made a typo on the file and PHP is bombing out. Can you access the dev site via FTP or SSH? If so, you should be able to download/edit the file to correct your mistake.

Deactivate all of your plugins via FTP and try again.

Did you try what I suggested? Your functions.php file doesn’t really do much to help us as it looks completely fine.

Ok, so you’ll need to do try the same but with your theme while leaving your plugins deactivated.

http://wordpress.shadowlantern.com/change-wordpress-theme-in-phpmyadmin/

*Evan

No problem.

not a problem, it happens quite often 🙂