Only recently, when I start P2ATC the loading screen shows up and it appears in the taskbar, but then nothing else happens. I looked around a bit and tried to "Show windows stacked" method but that didn't help. Rebooting didn't help either and neither did re-installing P2ATC. Is there a log or a way to find out what's happening?

It's openning on a "Phantom screen".  Here's how to fix:

1)    After starting Pilot2ATC, Hover over the icon on the Taskbar
2)    A larger thumbnail of the program should show
3)    Right-click that larger thumbnail
4)    Select Move
5)    Hold down the Right Arrow key on the keyboard until the program comes into view
6)    If that doesn’t work, hold down the left arrow
7)    Once the window is in view, use the mouse to move it to the desired location.
😎  Shut down Pilot2ATC so the location will be remembered.
 

Thanks for responding Dave. It's funny, I just fixed the issue and came back to post how I did it and then found your reply.

I originally tried the move window solution, but may be I didn't do it correctly because it didn't seem to work. Then I went through the big circle of uninstalling P2ATC as well as SQL Server and then reinstalling, only to arrive at the problem.

Then I did right-shift + left-clicked on the P2ATC window in the taskbar (I think that's similar to right-clicking the large thumbnail), and this time clicked either Maximize or Restore, I forget which one now, and P2ATC popped up.

In the end, yes, it was a phantom window issue. Glad to have it working again.

Thanks.