I would hook them up to a battery charge for at least a day, then check their voltage etc.
Check out this manual, lots of good info, at this link
http://www.batteryminders.com/conten...lus_models.pdf
I have a 12117 charger for bike that I am about to hook onto my batteries and am looking into another one, maybe solar version for our 5'er.
Desulfating looks to be the thing that may bring them back to life.