My laptop charger is beepign and won't charge my computer....?

last night in the middle of writing an essay my laptop upturned off. so i plonk the battery back in and it turned out, but the screen was dim truthful i realised the charger wasnt working even Tai it was plugged within. when i checked next to that little box that the charger has [the box that connect the electric top wire and the wire that goes into ur laptop], it was beeping. whats flawed??? ive had it since october and its been working fine until ultimate nite..and now it wont work at all.