I would try re-installing the search widget. (yes, the search bar is a widget.) My standard Android power control bar widget got screwy and too wide for the one home screen for no good reason. I just pulled it off and re-installed it and it was fine. It may just need re-initialized after the hard reset. Sorry if you know how to do this, but in case you don't: Long press on it until it vibrates, pull it down off the screen. Long press on the home screen until your install menu comes up, press "Widgets". Scroll down to "Search" with the magnifying glass. Press it. Your search bar will re-install. See if the voice portion is with it this time. Hope that helps.
these are instructions for the MTG3, but the Hero should be much the same.
