Permalink errors

Hi i recently change my theme on wordpress and since then I'm unable to use postname permalink Or any ither, inky the plain format works. I tried everything from changing the .htaccess rules to restarting the server. Please help me fix it.
Thanks for replying.
3 days ago I was editing my WordPress site and actually the ssl got expired so I went to cyberpanel to issue a new one. A first everthing looked ok but when I tried to open other links except for the homepage they showed 404 error page not found on the server. Then I tried everything even uninstalling my theme and reinstalling it but it didn't helped anything. Then I tried to change the permalink type to plain and everything started working. But yesterday when I was trying to connect ezusy(a plugin) to my woocommerce site it showed the same 404 error. Please tell me what's wrong.
Many thanks website url:
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