Question
we recently bought a house that has a irrigation system,,,,,,,,,the panel box was checked, the fuse is good and the battery is too,,,,,,,,,had someone check it  and said that the back flow needs to be replaced,,why is that,,,,,,,,the valves are turned on and i believe something is turned off b/c no water is coming out........when its turned on manually no water comes out so i think there is a valve turned off somewhere..........please help

Answer
A faulty backflow preventer can very well keep water from flowing into your system.  Unfortunately, it is very difficult to check them yourself.  You need a lot of gauges and training.  Since someone specifically told you this is the problem, I would tend to believe them unless there is good reason not to.