Pull the loose laminate upward from the countertop until you reach a portion of the laminate still secured to the counter.
Scrape away any debris from under the counter, using a putty knife.
Wash the countertop with a pH-neutral cleanser and a sponge. Rinse the cleanser away with clean water, then pat the surface of the counter dry with a clean cloth.
Spray a thin layer of contact cement onto the underside of the laminate and across the surface of the counter. Wait three to five minutes for the cement to dry to a slightly tacky state before applying the laminate to the underlying countertop surface.
Press the laminate finish firmly back onto the countertop. Roll over the laminate with a roller pin, using firm strokes to make certain the laminate contacts the counter completely and that no air is trapped between the two pieces. Allow the cement to dry overnight before using the reattached laminate.