Yeah, I was unable to track my post made on "infected files" a few days ago. I had to search for long. Besides clicking on a user name has a precondition of being logged in , or to track him thru other posts. I was suggesting an easy and helpful feature commonly found in discussion forums.
Ok, here's my point. If you made a post on "infected files" a few days ago, and someone replied to it, then you would easily find it by using the "Show new replies to your posts" that I've suggested 3 times now.
If it doesn't show up, that means nothing has changed or no posts have been made to that thread.
If you still wanted to go back to the post that you made, you can use the other suggestion that I made, which is clicking on your name (or clicking "Profile" as craigb suggested, which is the same thing as clicking on your name), then click the "Show last posts of this person". That will give you a list of EVERYTHING you have posted, so you can find the thread again.
I'm not sure how this is still unclear to you.