WP admin and Plugins send me to website

HI,
I’m new to this but thought i was getting pretty well until yesterday.

Every time I click on “WP Admin” it takes me to my website and gives me the message “Oops! Page Cannot be found.”

Same thing happens when i click on:
“Plugins” and “Import”

Any ideas of what I can do?
and if you can dumb it down i would appreciate it :/

Thank you!

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