1998 jeep wrangler dont shift into 1st or reverse

I had the same problem, funny as it sounds but go to jiffy lube, oil rig, or one of those places and have them flush ur trans and have good fluid put in...

Give me some more information about this problem. May be i can help.

Sounds like something in your shifting cable, or linkage is corroded, or in need of lubrication. I would guess underneath where the weather gets it. See if you can spray some lube on it to get it to ease up. If it does, you are at the right spot.

check make sure the clutch master cylinder working properly along with slave cylinder. both master and slave don't have to leak fluid to be faulty, the rubber seal inside the unit could be worned and when apply pressure the fluid blow by or seep between the rubber seal causing the the unit not to work properly giving you a weak feel and pressure at the pedal. both unit have to work properly in sync. if one are weak you will have the same issue. clutch should have a good tight feel not sloppy or weak. pressure plate will also play important role, weak pressure plate will also give you a weak pressure feedback from the foot pedal and also will cause the synchronizer in the transmission not to engage and work properly. check this basic item fist before messing with your tranny. clutch master and slave cyc are fairly cheap to fix and replace.

You are likely correct...sounds like the synchro is shot or the shift fork is somewhat worn. Is fluid full?
As long as the clutch does not slip and is engaging and disengaging somewhere in the center to just below center of travel, it's OK.

if this is a 5 speed manual transmission...all you need to do before putting your jeep into reverese is puting it into first gear and then shifting it to reverse to avoid any grinding or problems shifting into reverse...this isn't a problem just a poor jeep design by not installing an extra gear to eliminate this grinding or shifting problem

Try putting the car in neutral first. Try going in reverse while shifting out of 4wd.

This sounds like the linkage could have fallen or broken off. Have someone move the 4wd shifter while you look under the vehicle.

First check fluid. Make sure it's full and clean and does not smell burned (compare to another good car)
Converter failure is usually most obvious when trans shifts to OD. if shift is late or makes bang noise going in, you likely have a problem. to check lockup, after od engages, lightly touch brake, trans should momentarily shift out of od. Whining is usually due to low fluid. Also check transfer case and both differentials for proper level and leaks.

shift tranny from 1st-3rd if engine revs up clutch needs replacing