Oil pressure in truck went from high to low, no oil in the truck & no oil leaks

What is your question?

i was driving when I noticed that my oil guages was going down, I pulled over to check the oil, i discoverd that there was no oil in there, (however, there were no visualible oil leaks on my garage floor.) I put oil in and tried to drive it home when it quit on me, after a while it started back up with loud ticking noise. I was told that it was the oil pump but ill be better off replacing the engine. I need advice and directions.