ok i have a 1991 honda civic sedan and so far ive changed:
the distributor
cap and rotor
spark plugs and wires
the battery
and still the car wont start and it thrus code 15 i dont know what to do now your help is greatly apreciated thanks..

 

May be a bad ignition switch. If you disconnect the 2-pole connector at the dizzy, is there 12V between the black/yellow wire and ground with the ignition on?

 

Check mechanical timing.

After that, take a breath, relax, and think about it. Air, fuel, spark, and compression (and timing) are all an engine needs to run. Confirm that you are getting spark. Check your compression. Make sure your air filter is not clogged. Ensure you are getting fuel at the rail.

Code 15 is for ignition output signal.