My toilet won't stop running. I know I need a plumber but I need something to make it stop running. It's almost 11 p.m. I need help!

Shut off angle valve under toilet.

What type of filler do u have? Ball on rod or flow master? Is water in tank 1/2 inch below overflow pipe?

If water is going down overflow pipe, adjust float.

If ball, lift and see if water stops.

If flow master, lift arm controlling float and see if water stops.

If water still runs after these tests, replace flow master.

Good luck

Chuck

Chuck has the right idea. You must first tell us what's leaking.
Does the ball cock not want to shut off and it's leaking down the overflow tube?
It it leaking past the flapper so the ballcock keeps running?
Give us something to work with here
Regards, Tom