If you have been to a gig and found out, when you get home, that you have lost your coat, glasses, wallet or shoes (yes that last one really happened once) then this is what you need to do.
Phone the club on
If you do not get a call back in a timely fashion call them again but this time keep trying (say once an hour) until you get a person. The club is not always staffed and the person picking up your message will, chances are, not be the person who found your missing item the previous evening.
The club cannot keep everything that gets left there forever...so call as soon as you can.
I hope you are soon reunited with your property.