Menu / Show All will reveal the icon if you inadvertently hid it. If you have folders on your home screen, look in them. It's possible you dropped the icon in a folder while moving it.
Pull your battery with the phone on. Leave it out for a few seconds, then put it back. That will reboot your phone and may restore the icon. You didn't delete the app, did you? Does it still show up in the Options / Advanced Options / Applications list?