Toilet float adjustment screw is stuck - how can I fix this?
If you opened the screw two far or unscrewed it lift up on the ball and tighten the screw. To me it sounds and looks like you backed the screw out of the actuator.
Fill valve kits that replace the valve and float in my area or only 12-12$ fill master and they come with the needed seals and instructions.
I would lift on the ball and try to tighten the screw to see if you can get it to go back into the plastic actuator.