2005 buick rainier wont shift past 2nd gear

I found this info for shift knob. Note the picture. After the shifter is off, maybe a spring loaded piece sticking up from shift rod, Push it down and shift it. I'm just posting this from memory, different vehicle. You can talk to your local autostore or service department at local dealership or local salvage yard or ebay for a new part.

YOU NEED TO SEE A TRANSMISSION MAN, THIS DOES NOT SEEM TO BE A JOB AN END USER CAN TACKLE. aLMOST CERTAINLY GEARBOX TROUBLE I am afraid
Good Luck with it

Sounds like the reverse band or servo has gone out. Transmission shop needed for a confirmation.

you can shift it at transmission by hand to neutral or park and have someone inside start the car and you manually put in gear under hood and drive it to shop or garage, wherever

Best Manuals You just go to the link I attached I'm sure you will get the solution of your problem

if the car is on a steep incline could prevent it from engaging

When you are finished with your 4 wheel drive,put the transmission in neutral, disengage 4 wheel drive and shift to reverse then back up a couple feet before shifting to forward gear.

transmission shift valve is probably stuck...will need to be looked at and serviced.

You probably have a sensor going bad and the trans is protecting itself by going into limp mode. Check the fluid level while trans is warm and car is parked with engine running.