This may be a plugin or theme conflict. Please attempt to disable all plugins, and switch to the default Twenty Twenty theme. If the problem goes away, enable them one by one to identify the source of the problem.
If you can install plugins, install Health Check. On the troubleshooting tab, you can click the button to disable all plugins and change the theme for you, while you’re still logged in, without affecting normal visitors to your site.
Thank You for your reply.. i tried above suggestion, however, still my issue is not resolved i also download the health checkup plugin, but same is also shown 0 critical issue.
My Main problem is In new post, in setting, beside the document there is a Block button & in block button there is no any block & and also + sign is disabled.
Please help on urgent basis..
There is only classic editor & in classic editor there is only option of Paragraph
I found the solution
its in my profile, by mistake i ticked the on the Disable the visual editor when writing