Help with my a/c please

there are several reasons for the air to stop being cold suddenly. the belt which drives the air conditioner comressor may have broken. that usually causes some noise for about 5 to 10 seconds, then nothing further.  the high pressure hose from the compresson may have failed which would cause a loud pop with a cloud of condensation (looks like smoke) from under the hood. (you probably would have noticed the cloud).  the cold air is funneled into the interior of the car controled by vacuum actuated doors in the tubing.  failure here would not cause any noise.  the compressor may have overheated and locked up.  this would cause a lot of squealing by the drive belt and then the belt would break and be thrown off.  You do not have go to a dealer to determine the problem if the belt is gone, but I would not go to just any repair shop. Seek a large air conditioning specialist shop.  you may have to pay a little more, but unless the repair is done correctly, it will probably start blowing hot in a sort time.