My 4wd was working. Parked for four weeks now does not work. Why on 2002 Chevrolet Trailblazer

lights work on dash switch but does not ingage in to four wheel dr.

Asked by for the 2002 Chevrolet Trailblazer
check the solenoid on the front diff
(correction) The 2HI light is lite and it is stuck in 2HI. The other lights do not lite or ingage.
could be a bad switch