i have bad transfer case motor. it is stuck in 4wd hi. does it have to be in 2wd on 2002 Chevrolet Silverado 1500

when i change th motor and if so how do i get back in 2wd with the bad motor?

Have you tried tapping on motor with a small hamer to see if it will then shift? That is the best way to check the shift motor to see if it is just stuck.