i can install driver for xerox 7345 network printer it gives me message that can't install the software because it is not currently available from software update server

Are you downloading it Mac Store Updates?

There appear to be two drivers on this Xerox page --one for the Built-in controller, and one for the EFI Fiery controller:

http://www.support.xerox.com/support/workcentre-7328-7335-7345-7346/downloads/en us.html?operatingSystem=macosx&associate…

You could also try "generic postscript" driver in Mac OS X, which should get the printer printing, but would not provide advanced features like tray selection and two-sided printing (if so equipped)..

OS X Yosemite: Reset the printing system