How do I access the the markplace when Linden Labs changed my username to my avatar nickname?

[Lindal Kidd]

Well, if you don't want to call, you can file a Support Ticket.  But you'll still have to wait...probably a lot longer.

[Lindal Kidd]

Well, if you don't want to call, you can file a Support Ticket.  But you'll still have to wait...probably a lot longer.

[Rolig Loon]

There is no gold membership, so I suspect that you mean that you have paid for a Premium membership. If so, you don't need to wait for a few days to get a response to a support case. You have already paid for Live Chat, so call them and ask for help. If you are no longer a Premium member, of course, you have no choice. Your only option is a support case.