This problem could either be caused by a defective ignition switch, a weak or discharged battery, a defective neutral safety switch, a defective starter solenoid or a defective starter motor. You could save a bunch of heartache, money, and guessing by making some simple tests to narrow down the source of the problem:
Try turning the headlights on; and then watching their brightness when you turn the ignition key to the start position. If the headlights dim way down or go out when you turn the key; the battery is either too weak to drive the starter, or the battery cable clamps and battery posts need a thorough cleaning and tightening, or the starter motor is internally shorted. Try cleaning the battery cable clamps with a tapered reamer type battery cable service tool, and reinstall and tighten them until they cannot be moved by hand. If the problem continues; have the battery load tested by a shop or store that uses a battery load tester (NOT just a voltmeter or a hydrometer). If the battery fails the load test and will not accept a charge; it must be replaced. If the battery accepts a charge and then starts the truck; the alternator may be defective; so it should then be tested for maximum power output under a load. If the battery tests good; but the starter still doesn't run, and the lights still dim way down when the key is turned; replace the starter motor.
On the '95 Ranger 4 cyl, two different types of starter solenoids were used. The solenoid is either mounted on the inner fender; as shown in the following link (http://www.rockauto.com/catalog/moreinf
o...), or on the starter; as shown in this link (http://www.rockauto.com/catalog/moreinf
After you have a battery that tests strong (it takes a LOT more battery power to run the starter than to run the radio and bells): To test the fender mounted solenoid, connect one end of a jumper wire or remote starter push button switch to the heavy terminal bolt on the solenoid that is attached to the positive battery cable. Then connect the other lead of the push button switch to one of the small terminals on the solenoid, and briefly press the button (or touch the end of the jumper wire to that terminal). The solenoid that is mounted on the starter can be tested the same way; but there is only one blade terminal instead of the two small terminals. If the starter runs when you connect power to the blade terminal or to one of the small terminals; then the problem is in the ignition switch or neutral safety switch.
If nothing happens when you touch one small terminal; try touching the other small terminal. If nothing happens when you touch either small terminal (or the blade terminal on the other type of solenoid); then either the solenoid or the starter motor is defective. You can determine which of those two parts are bad by placing a heavy screwdriver or metal bar so that it briefly touches the top of the two heavy solenoid terminal bolts at the same time (BUT DON'T LET THE METAL BAR TOUCH ANY OTHER METAL ON THE TRUCK). If the starter runs when you short across the solenoid terminals; then the solenoid is defective. If the starter does not run when the solenoid is shorted; the starter should be replaced.
To test the neutral safety switch; move the shift lever to the Neutral position instead of Park, and see if the starter works in that position. If the starter works in neutral but not in Park; you can just start it that way from then on, or replace the neutral safety switch. If the starter does not work in either gear position; I would replace the ignition switch first. If it still doesn't work; then replace the neutral safety switch.