Do you mean the calendar pane on the right side??

Thanks for the response, but the events listing in the calendar is on the top of my screen, next to the inbox for the specific email address. I call it a folder. That's what is now missing. Does this clarify the situation??

Please provide a screen shot per https://support.mozilla.org/en-US/kb/how-do-i-create-screenshot-my-problem

Thank you for your assistance, but I have now solved the problem. I re-installed lightening add-on and it brought back all the missing data. Cheers, Cuey.