Back in 2000, we had a very early morning flight out of Philadelphia to WDW so we stayed at the airport hotel the night before. We checked out around 5am for a 6:30am flight with our two kids, aged 8 and 6 at the time.
At 10pm that evening, when finally settling the kids in after a long day of travelling and enjoying the Magic Kingdom, my 8 year old daughter asked "Where is Panda Mom? I need Panda".
Panda was a beanie-baby-sized bear, very well-loved, and something she slept with every night. Panda was no where to be found, but we KNEW he was with us the night before in the Phila. hotel. All I could figure was he got wrapped up in the blankets and no one saw him and packed him before we left.
She was inconsolable, and I got right on the phone to the hotel. I really didn't expect to get him back; I figured he got wrapped up with the sheets and headed to the laundry. Housekeeping was closed, so the hotel manager on duty at the time said he'd leave a message and they'd get back to me if they had it. I left our room's phone number with him, and told my DD that I did all I could. She fell asleep finally, but I could tell she was deflated to not have her dear Panda.
The next day, we left early and spent the day at the parks. Returned to our room around 6 that night to change for dinner and there was a message from the Philly hotel...they FOUND Panda and needed instructions on how to get him to us!
Rather than risk him getting lost a second time, our DD agreed to let him go 'home' and she'd see him there. The Philly hotel shipped him to our house at no charge, and he was waiting there for us when we returned. I sent a letter upon return thanking them for making a little girl very happy.
So...in our case...a very happy ending. If you can give an accurate description and where you believe it was left, its entirely possible they find what was left behind and get it back to you.
Good luck!