You can try dismantling the calipers, cleaning and greasing sliders, most of the time the caliper corrodes and lifts the clips the pads sit on so they wont move freely. If its been sat for any length of time prob best having calipers reconditioned/ replaced. I left mine standing for 4 months and had to replace both rear calipers and managed to save the fronts with some cleaning, filing and greasing!!!
Good Luck