My dashboard and site have become one!

Can somebody please help? I’m new to this and have been fiddling around with my dashboard and something has gone wrong. It was either because I put 7 things in the sidebar when there should have only been 6 (the last of which was a really big Twitter box). Or I fiddled around with an address on the settings page – I can’t remember exactly what it was but i changed an address from https://www.mummyratesit.co.uk/blog to just .co.uk
Now when I go to anything in the dashboard it goes to a very messy live site. I can’t do anything in the dashboard at all. I’ve tried going back but that doesn’t work either. Thanks