We are very sorry that your gecko is lost.
Sure, you could write something like this:
“We lost our gecko, Chuck, on the weekend and the kids are heartbroken! We’ve been out searching our neighbourhood, but no luck yet. Chuck is about 2 inches long and he’s a dark green colour. We’re hoping someone saw him or picked him up by accident, but after a week we’re losing hope. If you see him please call us at (phone number). Thank you!”
However, it’s not an optimal solution.
How about creating a flyer instead?
You can download a free lost gecko flyer below: