How do I fix a leaking hose vacuum breaker. When the garden hose is open, a lot of water spills out of the holes in the vacuum breaker. I was trying to remove the whole vacuum breaker but the screw on the side was cut off. I have this problem with 2 out of 3 vacuum breakers outside my house & its damaging the outside wall of the house.

These vacuum breakers are installed in such a way to make them difficult to remove. The only way to get them off is to VERY CAREFULLY cut them off (without damaging the underlying threads). A good plumber should be able to do this for you. These vacuum breakers are not repairable.
Another option is to just replace the hose bibs. If they are threaded into a fitting, this is pretty easy, just turn off the water to your house and open all of your hose bibs. When the water stops running, unscrew the old ones and screw in new ones.
If they are soldered on, again, I would recommend a plumber. If you know how to solder, then you can do it yourself (it is an easy job) but I don't recommend this as a first soldering job.
Finally, don't scrimp on the replacement valves. Buy good ones (usually around $4 - $7 each). You don't want to have to do this again next year.

how do i fix a leaking hose vacuum breaker. when the garden hose is open, a lot of water spills out of the holes in the vacuum breaker. I was trying to remove the whole vacuum breaker but the screw on the side was cut off. I have this problem with 2 out of 3 vacuum breakers outside my house & its damaging the outside wall of the house.

The screw on the side is designed to snap off once it is tightened to prevent the removal of the VB.

It's a fairly course thread, so I generally remove it with an easy-out (http://www.amazon.com/Easy-Out-Piece-Set-Case/dp/B0002UJNWE) and the appropriate size drill bit.

You could also try cutting it off with a Dremel tool and abrasive cut-off wheel -- Cut deep enough twice to expose the top of the bibbs threads, but not deep enough to damage the threads and then pry it off with a chisel or wide blade screwdriver.