Safari not opening on my iMac with macOS Sequoia 15.5

iMac Retina 5K, 27-inch, 2020, Sequoia 15.5. The Safari icon in the sidebar won't open.

When I click on the Safari icon in the Applications folder, I get the message: "The application "Safari" is not open anymore."

My software is up-to-date.

How do I get the Safari application back on my iMac?

Thanks for help.

[Re-Titled by Moderator]

Original Title: The application "safari" is not open anymore.