At Hogwarts, I used to put up signs at the end of term asking for the return of my lost items. They usually came back. Signs can be very practical.
After that, after the war against Voldemort, there was something lost, and I couldn't have said quite what it was. No one took it, as they did with my books and sundries, but it was still very gone.
You can't put up a sign looking for a piece of yourself. No one would know what it looked like, or what to do with it if they found it. In that case, signs aren't practical at all.
But then it sat down right next to me, in the form of someone I hardly knew. I wasn't positive at first, but I had to find out, didn't I, because how else would I know? So when he left, I followed it.
As it turned out, it wasn't an it at all; it was a he, and he was George Weasley. There was a piece of him missing, too. He might not have known what it was, but he was looking for it all the same. And I wanted to help him find it. After all, he'd helped me.
That first day he handed me a wand, but it wasn't a real wand, because it turned into a fish, but it wasn't a real fish either, it was a joke. That was funny, because it was two different things that it really wasn't. Jokes are supposed to be funny though, so they were successful, and I laughed. He didn't laugh with me, probably because he knew it was a joke, and when you know something is a joke beforehand it isn't quite as funny. But he did almost smile, and a piece of me came back.
The next day he came looking for me, and he gave me a wand-fish-joke of my own. He sat down with me again, and when he spoke I heard—though it's not what he said—that he wasn't positive, but he was trying to find out, just like I had, because how else would he know? So he came to find me, because he was following it.
As it turned out, his it wasn't an it at all either; it was a she, and she was me.
He asked me to follow him again, and another piece of me came back.
Piece by piece he returned what I had lost, what he had never taken but somehow possessed, until I was finally whole. I handed his pieces back as well, what I'd never even known I had, but he didn't know where they fit. I waited for him to figure it out, because that was the one thing I couldn't make him see. Finally he was shaken, and as all of his pieces fell into place, I gave him the last one I had to offer, the only one I'd ever really had, and he found what he had lost.
I don't need to put up signs now, because my items have all been returned, and I'll never look for them again. I know where they're found.