If you have an explorer, you should have electric fourwheel drive. If you do, you can manually change back into two wheel high. If you'll lool under your truck, on the transfer case, there is a servo(electric motor) attached to it. If you remove the entire servo assembly from the tranfer case, you will see a small knob protruding from the transfer case. It should be sealed, so don't worry about fluid leaking out. It should have 2h 4h n and 4l written in the metal around the knob. You can take a pair of wire pliers and turn the knob until it points back to 2h. But I strongly recommend getting the problem fixed immediately. It could be that the servo is bad, it could be a bad switch in the dash, or it could be the four wheel drive computer has gone bad. You need a mechanic to check to make sure before you replace any parts. Hope I was some help.