How do i open a lock after the knob has fallen out the other side?

I was locked out took the screwdriver took one side of the door knob off. I pushed the other one through. All that is in the door hole is an adjustable latch and it is still locked. I have a light and about 2 screwdrivers to work with. Also this is not a door that uses a key. It is a door inside the house and I am on the other side of the one that locks.