Horcruxes

Okay, I'm a little confused on which ones they've found and which ones they haven't. Do you think that the locket was already destroyed or not?

And also, what are the importances of the locket, and all the others? When they talk about the trophy and it already being destroyed, when and where did that take place?

Gosh, I think I'm going to have to reread this!!

One horcrux was destroyed by Harry in the Chamber of Secrets. It was the book that Tom was in. I'm not too sure about the locket being destroyed or not. But I was wondering why Dumbledore didn't try to destroy the locket when they got it, still not knowing about the note inside.

Yes, the locket was destroyed, seeing as that's what the note said, (maybe) and the book, Tom Riddle's diary was destroyed and obviously Marvolo's ring, that Dumbledore was wearing on his finger.
Basically:
Locket (maybe)
The Diary
Marvolo's Ring

Possible One's that were not destroyed:
The Cup
The Snake
Something of gryffindor or Ravenclaw

As I posted in my question there is mention of a locket found in 12 Grimmauld in Order of the Phoenix. I think that although Regelus may have found it he may not have had the power to destroy it

ok but we do not know that regulus is RAB he might be but he is not the only option