i am not able to open my websites

i am facing issues with speed also the premium membership is depend on your support.

ERROR I GETTING:Application error
An error occurred in the website and your page could not be displayed. If you are the website owner, check your logs for details.


I deleted w3 cache as it is not supported here.


now facing another issues 404

in menu section not able to see any content


Head to wp-admin, login go to settings, permalinks and choose default.