where the cable is plugged into the laptop you mean? if the laptop itself was dropped, sounds like the connection internal to the case. is it in warranty? (and dont forget, anything sold in the EU now is covered under a 2 year guarantee). if it is, return it to the seller and claim ignorance.
Sigh. Back to the drills me old mate. Check if power is being delivered consistently at the plug from the power supply (you can do this with a 24 volt bulb and a couple of bits of wire, or a small multimeter from Maplins for about 5 quid or less). The voltage to your laptop from its power supply will be between 16 and 18 volts.
If the power at the plug is consistent even if you twist the wires gently and move the plug about, the problem is likely to be with the socket inside your laptop and probably the soldered joints which take the power from the socket into the computer.