Problem solved ??
Thank you Steve Stern. I have deleted:
wp-content/plugins/wp-maintenance-mode
like you wrote before.
Website work on fonton and fontend.
Can I have a litte 2 quetions more?
Is deleting plugin directory safe for website?
Before I was working on joomla and I don’t remenber such solutions like deleting plugins directory (I know.. wordpress is another CMS).
Can I once again install wp maintentance plugin? – I want use maintentance mode, this is my purpose.
Thank you once again for help.
