Problem with Lumicycle lights!

Hey, I have a set of lumicycle lights with the lithium-ion battery. The problem is they haven't been touched over the summer due to being packed away after moving house. Now when I plug them in to charge them its like the charger cant see the battery, they wont charge! Is there any way of fixing this or do I have to buy new batteries? They are only just over a year old. Any help appreciated. Thanks.
If the battery is totally flat, it may not be detected by a 'smart' charger. It may be possible to use a basic charger to give it a partial charge, then the smart charger would be able to detect it again.
Take precautions with Li-ions though, risk of fire or explosion if mistreated.
Cheers for your input. I was on to Lumicycle and they said to send the batteries back to them and they'd have alook.