If your Ranger *does* have one (possibly added aftermarket), it's likely located behind the glove box, but access may require partial or complete glove box removal. However, you should carefully examine the area behind the glove box to be sure; it may not be there at all.
Before starting any work, consult your owner's manual. It's the best source of information for your specific vehicle. If it doesn't mention a cabin air filter, it's highly probable your truck doesn't have one.
