How do I recover my wp-admin login?

I just created a sub-directory and installed a second install of wordpress for 'Directory' plugin. It seemed ok, but when I exited and came back, I needed to insert user name/password. The one for my main site doesn't work. I tried deactivating and re-activating but can't get to it's dashboard. Should I just delete the entire directory and start over? I've obviously missed a step (like create admin). Thanks so much for any help.