I work with drupal 7.34, I want to use my custom theme, I have created theme but when I have mark it as default theme mysite.com/?q=admin not showing login page to login administration page, when I change default theme to seven or any drupal themes works correctly.
In other words I want to have my custom theme but administration theme must be other.
Can anybody help me?
I don't know if I'm getting you right. You want to use your custom theme as default theme and also as administraion theme, is that correct?
So you already set it as default theme and the administration theme under admin>appearance as Djouuuuh suggested to 'default theme'.
When I try ?q=admin to login it doesn't work with any theme. Try yoursite.com/?q=user instead.
Another source of trouble could be the overlay which you can disable under modules or just for your user in your profile under /?q=user
admin>appearance"Admin theme" in the bottom of the page. - Djouuuuh