Any hobby/electronics store should carry the right connectors. If you paid attention during (or even took) shop/electronics class you should know enough of the basics to competently solder the connectors.
If it's a wall charger toss it out as soon as you can and get a "real" charger any RC/hobby shop will carry the charger that you should be using.
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE