I have a 1995 Mercury Tracer the spark plugs is not firing What could be the problem?

Check the battery, distributor, coil, plug wires and even the plugs themselves.

You need to replace the spark plugs and the wires?

Last_Jud got most of the things you need to check - make sure also that the timing belt is good - not slipping or broken.

check to see if you have fuel if yes coil in no fuel no spark could be crank senser or moduel

Check the rotor in the distributor cap. Those were bad about burn through, thus the spark goes right to ground inside the distributor from the rotor to the shaft.

YOU MORE THEN LIKELY HAVE A DEAD CYLENDER AND YOU MIGHT NEED TO HAVE A VALVE JOB DONE AND CHECK THE COMPRESSION IN EVERY CYLENDER WITH A COMPRESSION GUAGE THAT CAN BE BOUGHT AT A AUTO PARTS STORE SO THATS WHAT WE HAVE DONE TO SO MANY VEHICALES AND IT HAS FIXED THE PROBLEM THANKS AND GOD BLESS. AND HAVE A GREAT DAY..