1996 Volkswagen Jetta won't heat

Is your engine heating up normally (temp gauge registering normal operating temp)?
If so, then you need to start checking out the heating system. A decent manual would help in the investigation. Essentially, you must determine if engine coolant is getting into the heater core and circulating. Does the heater blower motor come on when you turn it on? If the engine gets warm like normal and your heater blower motor comes on as normal, you may have a problem with your heater core - hope not because they are a headache! But, it's not uncommon. Hope this helps.