Am I too late to get the leo coin from Alexandria caslte now it has been destroyed?

Unlike the Coffee quest, the coins in the Stellazzio quest can be found at any time in the game (they're not in areas which become sealed off later in the game).

Later in the game, once you get the Blue Narsciss or an airship, you can return to Alexandria and head up to the ruined castle. Most of the castle is indeed destroyed, but the front courtyard and the left tower with the statue which takes you to the harbour is still intact. Inspect this area to find the Leo Stellazzio (I can't remember exactly where it is found in that area though).

its in the top corner i believe

Top left to be exact. (I think :S)

Oh! Well, I do have the airship and did look about there and didn't find it, I guess I will look again.

Yay, got it. Now I have Ark etc! Thankyou, I was looking outside the door, silly me.

How did you get Ark...from Leo...?

Well, I didn't. I was just updating you on the progress of my game.. :(