"He who marches out of step hears another drum." ~ Ken Kesey
If he messed with the htaccess file then he messed with the permissions to the files that you cannot access..
The htaccess file among other things sets permissions.. Joomla is a framework built on top of php. So even if the server have theirown htaccess file, the community that created Joomla could have also included their own that the server would use instead of their own. If I were you I would have pulled down the current file on the server and replace with the original as to troubleshoot because the original was working fine. The original problem was in the browser not the server. But of course after doing that clear cache and history..
I have a feeling it would be back to normal.. (web master- sanmar?? what's a sanmar?? sounds like spam to me).. When you get everything back up and running you should copy the complete working directory and save it to your hard-drive. What you should really have is a local machine running on your computer, like wamp server and have your working website running on it and then deploy a copy to the live server.. If anything goes wrong then you've got a working copy on your computer that you can just switch out and keep it moving. Right now you are fixing the car's engine while it's going 55mph..
Webmasters.com is my hostSan Mar is the supplier to whose catalog I linked
Did your host happen to upgrade the version of PHP they are running to a version that no longer works with your version of Joomla.....What version of Joomla are you running?...