1998 Ford Explorer • 4.0L V6 2WD Manual • 104 miles

Alright so I bought the truck of my neighbor about 4 months ago but its been sitting there for a year and ever since I started driving the truck after a bunch of times pushing the clutch in and out to shift gears and etc, my clutch would just lock up and be hard as a rock to push down. This has happened to me numerous times and if you just put force and push it down it will go back to normal? What is wrong with my clutch?
April 9, 2014.

Check the clutch pedal free play and Try adjusting the clutch pressure plate for a start

Apr 9, 2014.