No, all should not be lost. Do you at least have access to your database? Through phpmyadmin or something? If not, the host should at least be nice enough to do a dump of the database and send it to you (you'll have to prove that you own the site). That's where all your posts and other pertinent information is. Call, beg and plead for that database dump. With that info, you can rebuild your site. You might lose your images though.
If you don't know SQL or have an understanding of how WordPress uses it's databases, then find someone who does. You'll probably have to pay them, or if it's a close friend, maybe buy them a beer or something.
If you get that information, then do as I mentioned before and build your own version of WordPress instead of using theirs! You'll have full access to all files and database material.
One last note... if this host does not at least recover your database for you, find a new host and report them to the Better Business Bureau. Cause in my opinion, that's just poor customer service. It takes seconds to do a database dump...