Thanks for the response.
I went to that location and changed “Current Package name” to Modern and the home page still has the default theme and when I go to a product category page it is blank.
I tried both “Modern” and “modern” in case it makes a difference.
I can change the home page by going under CMS --> Manage Pages and changing the Custom Theme to Modern under “Custom Design” but I still get all the other pages blank.
The source of the blank pages is as follows:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<META http-equiv=Content-Type content="text/html; charset=utf-8"></HEAD>