Place a space heater on a low table or bench inside your garage. Position it near the garage door and turn it on. The space heater helps melt the ice more quickly.
Scrape any large chunks of ice away from the bottom of the garage door with an ice scraper.
Slide a butter or putty knife between the gasket of the garage door and the ground, wiggling it back and forth to remove any ice. The seal between a garage door and the ground is not solid, and under normal circumstances, a thin blade should slide under the door easily.
Continue working the knife blade between the garage door and the ground until the door is entirely free. At this point, the garage door can be opened.