The same freezer that holds your frozen pizzas and TV dinners can often bring seemingly-dead laptop batteries back to usable (though not quite like-new) condition.
Steps:
1 Put the dead laptop battery in a sealed plastic bag. 
2 Put the bagged battery in the freezer for about 12 hours. 
3 Take the bag out of the freezer, and let the battery warm up to room temperature, drying it occasionally with a towel if it appears damp. 
4 Put the battery back into your laptop. 
5 Charge the battery as much as possible, then leave the laptop on in order discharge it completely. Repeat this step 3-4 times. 
6 Your formerly-dead battery should now be much more usable, if not totally restored.
