Just to be clear too, if your car is stuck in low range and you are attempting to drive on pavement, at any speed but especially fast, you will wind up with a far more expensive repair bill.
Are there any warning lights? Have you checked any codes? Do the hi/lo lights flash when selecting them, or does the car indicate anything at all?
Have you tried going slow and trying to shift on the fly? Otherwise the motor or solenoid on the transfer case could be faulty, or possibly the sensor is bum.
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