Unable to complete admin login

I’m no longer able to access my site via the admin login. After entering my login and password in Firefox I get this message –

“The page isn’t redirecting properly

Firefox has detected that the server is redirecting the request for this address in a way that will never complete.

This problem can sometimes be caused by disabling or refusing to accept cookies.”

However cookies ARE enabled.

In Explorer I get this message –

“This page can’t be displayed

?Make sure the web address https://gayliawagnerdesign.com is correct.
?Look for the page with your search engine.
?Refresh the page in a few minutes.”

My website works in both browsers (though I’m seeing a problem with the shopping cart widget in the menu bar in Firefox that needs fixing).

I tried deleting the cache and cookies for both browsers. I also disabled my plugins folder via the CPanel – no effect so it has since been re-enabled. I also disabled and replaced the .htaccess file. Nothing has worked.

Website – gayliawagnerdesign.com

Please help!