Hi @glysolidin,
The Featured Image option should be appearing by default in the editor’s sidebar: https://i.snipboard.io/2JrLeY.jpg. If it is not appearing to you, you might have conflicting script with one of your active plugins. To verify, you could try disabling all plugins at once, then re-enabling them one by one and check back the option in post’s editor to narrow down the source of the problem. Before doing so, you want to enable Troubleshooting mode with the help of Health Check plugin to do private testing.
Yes I ahve done all the steps, directed by you. still no relief.
Neither TAG, CAtegory and Featured images tabs, non eof them are appearing.
