Can’t login to dashboard

I was trying to move the location of my blog to https://www.mydomain.com/blog
however I changed my wordpress address to the above and left my blog address as https://www.mydomain.com. Now I can’t login to the dashboard.

I have got to the login page by:

https://mydomain.com/wp-login.php

but after i typed in my password it goes to 404 page not found at the address below:

https://mydomain.com/blog/wp-login.php

Is there anyway to sort this out?

Thanks in advance