I tried to install your blogs mu theme and my website crashed

I tried to install your blogs mu theme and my website crashed. When I try to go to the admin page I get an error message saying “The website encountered an error while retrieving http://www.lifescinyc.com/wp-admin/. It may be down for maintenance or configured incorrectly.

Here are some suggestions:

Reload this webpage later.

HTTP Error 500 (Internal Server Error): An unexpected condition was encountered while the server was attempting to fulfill the request.”

Thanks