If your toilet keeps flowing from your inlet valve it could be your arm & float are stuck, if so lift gently to see if water stops and then let go of float it should stop if not there should be a screw with a nut on so that you can adjust the water flow, if not lift arm again unscrew float from arm & shake to see if water as got in if so buy new float.
If that all fails turn water feed off & buy a new ballcock & float these are not expensive.
yeswot
January 2010