When is an Ultra Light not and Can it be a LSA

[wmgeorge]

Let me toss this out. Granted I am not a pilot and just learning, but for most of my 74 years I have been gainfully employed in some pretty techy fields thank you. So what IF the air craft in my question had been flown for a number of years as a Ultra Light or whatever but clearly qualified as a Light Sport Air Craft why can it not be inspected and certified air worthy and assigned a N number? Just because a deadline had passed, the air craft has flown, had logged time on the books. There are NO proceedures within the FAA to re-inspect on a case by case basis?
When I was in the USAF on the flight line I saw a lot of repairs. I was an air craft electrician, mid 1960's Cessna 310s to B52s.

What happens to a air craft after damage say from hard landing is it assigned to the junk pile never to fly again?