I have a Bryant central heating and cooling unit but but the pilot light when out how do you relight it?

Ar you sure if has a standing pilot?

If so you should find a knob that essentially says off-pilot-on and a push button. Some push buttons are a piezo-ignitor.

Move knob to pilot. Push button. Light pilot with match. Hold button for about 3 minutes. Release.

If these are not the right instructions, post a pic of the area.

There are electronic ignition systems too. Post a model #.