Turn off the water supply to the toilet
Remove the tank lid and set it aside safely
Check whether the handle nut is loose
Tighten the handle nut by turning it counterclockwise if it is reverse-threaded, or clockwise if standard-threaded
Reconnect or adjust the lift arm if it has come loose from the handle
Replace a bent or broken lift arm
Replace a cracked or broken handle
Replace the flapper chain if it is tangled, broken, or too loose
Adjust the chain so it has slight slack
Test the handle by flushing the toilet
Reinstall the tank lid
Turn the water supply back on if it was turned off