I have tried to edit build.prop for on screen navigation keys, but, unexpectedly get cleared build.prop file and got saved. What can be done to regenerate file? Should reinstall zip should solve it? Or can I copy file(build.prop) by extracting from ROM zip.
The prop file is right there in the zip (
/system/build.prop, same as the path on the phone) - you don't even need additional extraction tools to get it back.
Re-installation will also restore it, but at the cost of losing all prior modifications on
/system that you made.