What you describe is quite common, and is usually due to a fault with the DC power receptacle in the laptop. The receptacle is soldered to the motherboard, and the solder leads are often the only thing securing it to the motherboard, so they can get damaged or broken from taking the stress of plugging/unplugging/jiggling/jarring the connection. When this happens, the first visible indication will be an intermittent ability to engage the charger, but eventually overheating and shorting will occur at the broken solder joints, and this can lead to serious motherboard damge. The fact that you say you hear "a strange noise" means that you are already at this point.

If you are not comfortable with disassebling your laptop, you need to take it to a repair shop ASAP. Replacing the DC connector isn't difficult or time-consuming for an experienced tech, and the part itself only costs a few dollars. If you catch the problem before it gets too severe, simply replacing the connector will totally fix the problem. However, if you let it go and continue to jiggle the connection around, you will eventually destroy circuitry on the motherboard, which will obviously be a Very Bad Thing.

I have a similar problem, except its not the receptacle, because my mums charger works fine with my laptop, there seems to be no power going into the laptop, but its going through the adapter (because the light is on). So the problem must be in the charger, but I don't actually see a problem

I have the same problem, gonna mention it to my dad and see what he says, I have been jiggling the connection around and it seems to work, for now, but its very unreliable!