If you have never charged this battery (suspect is so as you do not have a charger) it may be past restoring. Lead acid batterys (or gell cells) do not take kindly to deep discharge and are easily ruined by discharging to to low a value. You need a limited current, constant voltage charge to do the proper charge on these. Many of the hobby chargers will also charge lead acid, I know the Triton will. It will behove you to check out www.rcbatteryclinic.com for some good advice on the care of all types of batteries.