Hello,
Thanks for the reply.
1/ Try to disable all the third-party plugins (including cache plugins), that do not come bundled with XStore https://xstore.helpscoutdocs.com/article/36-included-plugins , clear the cache of the browser, and check then. Maybe one of the additional plugins is a reason for the problem. Let us know the result.
2/ Enable debug mode in WordPress – https://wordpress.org/support/article/debugging-in-wordpress/ to find out what error appears on your site, it will point you in the right direction what needs to be fixed.
3/ Provide temporary wp-admin and FTP access, so we can take a closer look.
Create an account via Dashboard (Users > Add new) with administrator role http://prntscr.com/s3rc9m > provide us with username and password via the Private Content area http://prntscr.com/s5mao7 You can use any email for it.
If you do not know how to create FTP contact with your hosting provider, they will help you.
Regards