Garden tap wont turn on?

I presume that you just cannot turn the tap at all?
You can either renew the complete tap as a unit (they simply screw on to the elbow that holds them) or, if you unscrew the hexagon nut just below the turn handle and squirt some WD into the space there, the tap will eventually free off. If you can see lots of corrosion around the tap stem, have it replaced.

John
May 2009