Sounds like the database is toast. Do you have a backup? No? Does the web host have a backup? Ask them.
If the database is toast and the web host doesn’t have a backup, you’ve learned a hard lesson about making sure you have your own backups. Always have a database – and preferably a theme and uploads backup – at all times. Pick a backup plugin and use it: http://wordpress.org/extend/plugins/search.php?q=backup
Thanks for the quick reply…Luckily I do have everything backed up both with the plugin and at the host (thank goodness), but I wanted to see if it could be fixed without resorting to that or a rebuild.