my 2002 jeep liberty is stuck in 4wd

If you look in your owners manual it will tell you to shift from 2WD to 4HI and back to 2WD while the vehicle is moving at a low speed such as 4-5 mph. The system is designed to work this way. If it still does not return to 2WD after the handle moves and the dash light goes out, stop the vehicle and reverse for about 10 feet. This should release the transfer case back to 2WD. As far as 4LO, stop the vehicle, place the transmission in neutral before shifting in or out of 4LO. Hope this helps.

As for the "really wierd turning at full lock" this is normal for four wheel drive. It is meant to be used on surfaces that have some give such as dirt or snow/ice. As all of the tires are trying to go different speeds in a turn it binds the differential up some what, which on a forgiving surface is not a big deal as the axle/tire running behind can slip or spin and catch up. Hard for it to do so on dry pavement as it has good grip and traction and therefore binds. The tighter you turn the worse the problem becomes. I would recommend you not use the 4WD on dry pavement as you can do serious damage, and read the operating instructions in your Liberty's owners manual as it is very well written and specific to the system in your Jeep.

If this is a manual transfer case it can take a lot of muscle to shift the transfer case. Try moving the Jeep a few feet and try again.