Problem charging Dell battery. need help!

I am having the same problem with what appears to be a number of people regarding the dell battery not charging. When i plug in my dell ac power adapter it comes up with the message. " The AC power adapter type cannot be determined. Your system will operate slower and the battery will not charge. Please connect a Dell 65W AC adapter or higher for best system operation." I have 36% left on this battery and depend on this computer for my college classes. I need a quick answer!