After months and years of faithful work, your computer's keyboard may endure quite a bit. If you eat dinner while you work, it likely has crumbs from your sandwich and chips, or drops of soda from your drinking glass. If you have pets or live in a generally dusty environment, it could have hair and dirt underneath its keys. If the keyboard's space bar is sticky, any of these could be what's causing its ailment. Spend a few minutes cleaning your keyboard to unstick the space bar.
Position the can of compressed air's nozzle at the base of the space bar. Depress the button on the can to blow the air around the key. Do this on all sides of the key to ensure it is clean. Press the space bar to see if it still sticks.
Clean around the space bar with cotton swabs. Roll the tip of the swab between your fingers, and make the swab skinny enough to fit around and under the key. Do not use water on your keyboard as this could ruin the connection the keys have once the keyboard is plugged into the computer.
Pop off the space bar using a flathead screwdriver. Carefully pry the space bar from the base of they keyboard, and set it aside. Use the cotton swabs to clean around the now-empty area, then use the compressed air to get rid of any of the debris left behind. Replace the space bar on the keyboard.