Try and message the member if you can remember their name. If you can't the Bro's said old BM's would be archived and viewable at some point, so not all hope is lost for your situation.
I also had a trade in the works sending a Better Half around Chicago. If this was you BM me, can't remember your handle...i think it started with an "M"
I was suppose to do an in person trade for some beers I ws really looking forward to. For the trade I actually had to do so leg work to get requested beers. With The site down the date came and went so the trader can no longer trade....
Click "home" on the top left and then top right "old messages" if you guys exchanged BMs you should see it there with his username.