Rooting has nothing to do with the GPS, so evidently whatever you did to root it caused some damage to some files or some hardware. We can't guess what you did (some one-click rooting programs just root the phone, some do other things in addition), so we can't guess what's wrong. Run GPS Status to see if there's any GPS available to the system. If not you'll have to bring the phone into a shop and get an estimate. (If GPS Status sees the GPS and your location, uninstall and reinstall whatever app isn't running with the GPS.)