Hello,
What we can see of your bifold pin resembles either the 21-022 or 21-024 but we can't be sure since important components are missing. I can tell you that these pins are designed to work with the 21-204 bracket. I can't see enough of the original bracket that is still inside the track to determine if this is a match but this is a good place to start. Review the specifications shown on our product pages and see what you think.
If there are closet doors in the house that are still properly assembled, I would recommend using those to compare to our inventory and see how the disassembled doors should function. As for what you would need to put back, we would have no way of knowing that, unfortunately, since we have no way to determine what parts are missing.
