Roof Repair

I have an almost flat roof that someone here described as a "built up" roof, but now I'm thinking might be a torch down. The layers appear to be
1) Plywood 2) Felt 3) Particle board 4) Asphalt of some type..
The plywood and particle board on a small section are rotted. I would like to cut them out and replace them, but I have no idea how to fix the asphalt covering. I would appreciate any thoughts on the roof type, method of repair, and source for materials. I saw nothing at Home Depot or Lowes that might be suitable. And the roofer I called never showed up. ;-)
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