how do you fix the charger?

How old is it?
Does it work when the charger is plugged in?

It looks like it's the batteries that are dead... Your charger is probably working perfectly.

Any rechargeable batteries have a limited life span. It can be shortened by several factors:
Recharge when not fully discharged uselessly increase the charging cycles. Those only have a limited numbre of time that they can be recharged.

Leaving it totaly discharged for about a month or more will DESTROY any lithium-ion battery. ONLY brand new, never ever charged, lithium-ion batteries can be left uncharged for any period of time safely. Once you have charged them for the first time, you should never left them totaly discharged for more than a day.
If left unused, you should recharge them about once every 3 months. Always recharge them once they are totaly drained as soon as possible.

Electro
June 2012