Fatal error please help!

[xxxsamxxx]

Okay So I was trying to change the theme at michelle-williams.net/gallery but It would not change from the classic to the new one! I tried everything and it wouldnt work,then all of a sudden I get this error and cant access the gallery at all!

Critical error
There was an error while processing a database query

Please Help!!!

[Joachim Müller]

Enable debug_mode as suggested in the corresponding tutorial "Manually enabling debug_mode". Then post the error message you get (not the debug_output).