Tone Knob help?

[Mazz]

Right, the other week I let my friend borrow my Jackson as his strings on his SG were strapped, I went to his band practise and we noticed something while he was practising with it, somethings up with the tone, the knob doesn't respond at all and it's something I want to fix as it's my only guitar, the only songs that it was correctly set-up for was Creeping Death and one of their own, so atleast it's got a nice heavy tone on it, anyway, any solutions anyone? Please

EDIT: it's not my friend who fucked it up just to point it out, it's been fucked for a couple of weeks now so.... yeah.

[Trem]

knobs toast, or wires came loose.. not much more that can go wrong with a pot.