If they are individual cells (ie AA, D,C etc) the you may be able to rig a device to short them out if the voltage is below 1V per cell . leave them sit for a while, then try rercharging. It may take some time to get the to charge up again. when (if??) they do charge, discharge again by using a 1 Ohm resistor and short out again. repeat a few times and they may come good. It works most times for A/C batteries.
Or method 2:- Dispose of in a responsible manner and buy new ones....
Knowing you tho Tony (FSL Sir) you will have the resistors n stuff in the shed and will give the recovery a go..
