Ethereal

There's a "See their activity" button on your profile that you can click. Then on the left hand side, you can select "Topics" to display all your topics. I'm not sure offhand if it only displays topics you've both created and participated in, or solely the former.

I would use that, in conjunction with pasting the following into Google search and going through the various results:
site:http://sao-rpg.com ethereal

Or use see activity, look at the "posts" (topics only shows ones you've started) all closed threads should have their subject named changed to reflect being closed