Oh boy.......I went through this several months ago with a 3 year old dog that I adopted in early July. She had never been house broken (don't know why).

It took probably 3 months to get her trained all the way!
For awhile, I was posting something almost daily on Pet Talk- it was very frustrating! There are a lot of good people here with helpful advice.

What worked for me was first of all to have her on a leash in the house at all times, and make her always be where I could see her. That way she could not go without me seeing her. It seems she did not get the 'connection' unless I actually caught her in the act........then I would take her IMEDIATELY outside and tell her to go potty. When she finally went on command, I praised her a lot. once I finally caught her and took her outside, she was fine. Up until that point, just taking her outside and waiting was NOT enough for her.

And oh, the Natures Mirracle worked well for me.

Good luck!