Project Opening Issue

I want to playback a saved podcast project in Audacity 2.4.1. However, when I try to open it I get a message saying, "Error opening project…project is already open in another window. Problem is, I don’t know where the other window is to close it. Any suggestions?
Thanks for the support,

I rarely use Windows, but can’t you use “Alt + Tab” to cycle through all open windows?