I’ve written a test case using the Selenium IDE. I would like to run the test (using the play button) and I would like to switch to the Table tab so I can see the commands.
As seen in the screenshot, I can neither click the play button nor switch to the Table tab. Why?

You can execute test only when your IDE is set for Selenese (HTMl format) and not any other code format. Change it to Selenese (HTML) as following and it should work –