Heck my wordpress

hi guys,
a couple of days i noticed that site has been hacked.
somebody could enter to the panel (or i dont know how) and created an ADMIN profile. he/she published a post (around 2018) with normal words. also, harmed the current template. the template didn’t work well and i needed to change it.
still there is some problem with fast editing the posts and upgrading the plugins. in other words, about FAST EDIT from dashboard, when i change for exampple the date of a post, post’s row changes vertically and it fills the page.
Bigger problem, i cannot upload a photo, nor deleting a photo. I have to make all changes manually.
another problem relates to the update of plugins. none is upgrades. i cannot even install a new plugin by searching in the plugins’ library.

I wonder if somebody could help.
Yours,
Ben

The page I need help with: [log in to see the link]