I would have posted this yesterday except I could not see anywhere on the home page to locate these help threads. Only things I could find using the row of home page links were the consumer interest items, nothing about this forum. Frustrating 
Also I could not login using my original email and password from a few years ago. I tried the forgotten password link but it kept telling me that my email was already registered and would not let me use the temporary password.

Finally I registered using a different email. So now it thinks that I am a new member.
very frustrating experience.

I am not new to using computers and forums. I have been moderator for a forum for 10+ years, retired computer science professor, hi-tech programmer, etc. Hard to believe I had such trouble. Must be something wrong with your system. You'd think though that you would know about it if it were really broken. Very odd.
If you can fix my original login with FeMick@hotmail.com and delete my account with MultiMIPS@gmail.com I'll come back 
Anyway here is yesterday's post...
Problem solved, almost as mysteriously as it started. I made some planned changes to the app and went thru the process of setting up an AVD and editing the run configuration. Then the Select Device became un-grayed, the Run menu reverted to normal, and everything worked.
How did you all help? Well, you gave me a structured place to think and prepare how to fix this, and it worked. I had to think hard so that I could present the problem properly. That has been enough. Thank you for being here 