88 jetta, overheating

i just put my jetta on the road and it was running fine untill the next day it ran really hot and the light was on, i had no heat in the car but when i turned the heater off the light shut off aswell but still overheated. what could it be.

Which light?
No heat could mean that the coolant isn't circulating or that the heater isn't any good. It's possible for the impeller to fall off the water pump, it's happened to me. It could also be a bad thermostat. Check the temperature of all the coolant hoses. Make sure you have flow. If it's not too hot, squeeze the large hoses to see if you can feel the coolant flowing through it. Check your temperature gage, is it hot? Check for air bubbles in the coolant system. sometimes the pump gets air bound and you have to "burp" it by squeezing and releasing the hose.

And if it was unusually cold when this happened, it could be you dont have enough antifreeze-to-water mix in the engine. If this is the case, the 'liquid' in the radiator can freeze, even though there is water moving around in the engine head.