my 1996 ford ranger oil meter was low and a ticking noise in engine for a week. today the ticking went crazy and the truck shut down. how much to fix oil pump

This is not what you wanted to hear. I had a Ranger (Emerald Green) The low oil pressure was caused most likely by a rod end bearing that was for some reason worn therefore leaving a gap in the bearing mating survaces so oil was running out the sides of the rod end bearing causing the low oil presure. The ticking that went crazy was the rod end bearing that destroyed itself and fell into the oil pan.

Quite possibly you now have a broken connecting rod as for the reason it shut down unless the engine computer sensed ZERO oil pressure and shut off the ignition.

I can tell you your problem is probably not the oil pump.

I see the following instore for you
1. head removal / valve resurfacing
2. crankshaft polishing
3. rod end bearing replacement and possibly resizing

The oil pump is the least of your problems.

Just being honest so you can understand what could be instore for you. Sadly it is not cheap.