not allowed to admin panel

hi there. I’m admin of following site:

http://www.fantascoppiati.it/

when I try to go to admin panel through direct link
http://www.fantascoppiati.it/wp-admin/ … they tell me something like that:
“you need to be allowed to reach this page”.
Same happens to some other pages (profile i.e.).
On the other hand, I have no problem in going there from the bar if I add post, media, page, widget…
What can I do to solve it?
thank you!