iPod Nano stolen then recovered but can't prove it's mine

Hi,

My ipod Nano 4th Gen was stolen a few weeks back out of my car and has turned up for sale in a local second hand electronics store. The store has done a full reset on it to sell it on.

I didn't bother reporting the theft and now the store will only deal with me if I can prove it's mine - i.e. compare serial numbers.

I have no record anywhere of its serial number, and it doesn't show up in the Preferences-Devices section in my iTunes. Is there any way of accessing sync history on my computer or any other way of getting the serial number?

Thanks