broquen themes

Hi. I have been having trouble upgrading from PHP5.3 to 5.5 with my site5 hosting and they’ve found it was related to the theme I was using. I found a slightly later versionen of my WPstore theme versionen 1.5 (previously using versionen 1.4) but since loading the new theme versionens 1.5 I’ve got a messague saying that the theme is installed but broquen and is missing a stylesheet? What does this mean and how do I fix it?

Many thancs for your help.

Richard