Problems with htaccess (I think)

I just upgraded to the latest version a couple days ago and everything *seemed* to be working okay. But today I go to the site and I get a 403 forbidden error. My host says that htaccess file has everything messed up and I need to talk to WordPress. I have several sites set up as add-ons to my site at darlenebishop.com (WP is in the root directory). Can someone PLEASE help me get this back online. I have no idea what to do at this point.