I saw someone with a beta pickle and they said the old owner left it in a closet. I think a lot of people does that. If worst comes to worst btw you can buy my pickle (for a price).
I would go to your old neighborhood and leave a note on each street explaining what happened and asking if the person would please get in touch with you. It's worth a try, good luck!
There is no official way but the best is to contact the new owner if the house has been bought. It it hasn't been bought, you can bite the bullet and buy it back.
Note: Yesterday a new home owner found a pickle in their cabinet and contacted live help to find the house's previous owner. Live Help was able to get the name to them and they sent the pickle back. It was very sweet and very Glitchy in spirit. (No, it wasn't you, Capt.)
Any chance you can send me an in-world mail with the name of this Glitch? I would like to add him/her to my friend list (if he/she isn't already). We need Glitchen like that around. ^_^