I'm going to assume they are wet cells and the water has been cooked off so, unfortunately, it's toast. Wet cells require regular maintenance. After you replace your current battery, visit the manufacturers website to read through their recommended maintenance schedules and procedures.
I don't know what you were using to charge your batteries, but you might also want to look into upgrading your rigs converter/charger to help prevent this from happening again.
has a very nice lineup of equipment that should fit your needs.