I was driving my 02 a4 1.8t it smoked on the right side bottom of the motor and now it won't start it turns but won't start it didn't over heat or anything dose any one know what it might be

The catalytic converter will not cause it not to start. If the converter is plugged up a loss of power will be noticed, but it will still start. Same goes for the O2 sensors. You need 3 things for it to start and they are fuel and air, properly timed spark and properly timed compression. You need to find out which one is missing. Does it have spark at the spark plugs? Does it have fuel at the proper pressure at the injector? Does it have sufficient compression?

I checked the fuel pump its huming so it's working I have not checked the spark plugs what's the best way to check for sparks ?

And I don't know how to check sufficient compression I was driving and it just smoked from the bottom right of the engine and shut off I never lost power but it didn't turn and tell we waited about an hour but it dosnt start any more I drove it daily but a week before this happen I notice that the car won't start like it normally dose on the first try it was taking few try's and then this happens

Loosing power is the first symptom of a clogged catalytic converter but it can get clogged so bad that the vehicle will not start. I know had it happen to me before. To check for a clogged catalytic converter do this test at night let vehicle idle for about 5 - 10 minutes then take a look at the converter if it starts to glow red you have a clogged catalytic converter and also check the exhaust manifold I have seen them get clogged up also it will also glow red if clogged.

If vehicle is not starting you will have to drop the front end of the converter from the front of the exhaust pipe coming from engine then try to start vehicle if it starts up and runs that was your problem but no promises that is your problem.

have you tryed checking your oil and coolant levels? and was the smoke white ? what did it smell like? if it smelt like some one pissed on the ground thats antifreeze, if it smelt like a chainsaw thats oil leaking, if it smells like gas you either had the exhaust backed up or a gas leak. It chould also be a fired ground cable if it smelt like burning rubber or heated metal.