My garden tractor has been sitting 18 months and naturally the battery is dead. I have a 12 volt, 6 amp charger. Will this restore life to the battery or do I have to buy another? If the charge works how long should I leave it hooked up? 24 hours?
I finally got my push mower going with much thanks to this forum! Thank you everyone!

Yeah, leave it on for maybe 12 hours to overnight. And try it. If its a conventional battery where you add water and such. Make sure they are topped off. If not, bite the bullet and get another.