Transmission trouble?

I have a 1987 ford bronco,with 5.0 V8, automatic overdrive. The ignition went out, while the ignition was out i undid the linkage so i could still drive the truck, because the shifter wouldn't move. I fixed the ignition hooked linkage back were it was and now it wont shift from 2nd to drive. It will shift from 1st to 2nd. it never gave me any prob before, no slipping or hard shift, it was smooth and quiet. I believe its a 4 speed 1st,2nd,drive,and overdrive. Does any one know what the prob is or how to fix, is it as simple as changing the fluid & filter??