I've been driving this car for a while now. Everything els seem to work fine. But one day when i try to start the car for work. It just woundn't start. with no clicking noise or notting. just a silent hiss that i hear from the engine.

I would start with the battery terminals , see if one of them heats up after you have try to start the car if so clean the terminals then with the igition on check the points for spark, look at turning the motorby hand to ensure it has not seized, may check the status of the starter motor , if all else fails and you still have your hissing noise try to find that area and look very close maybe there is a problem there

Maybe its just old.