Turnoff valve doesnt shut off completely

[ihatefluidmaster]

So what happened before was my fill valve want working. INstead of replacing it right away, I had turned the water off with the nob right under the toilet, but my brother kept using turning it back on because he didn't want to use the bathrooms upstairs. Anyways it doesn't shut off completely and I need to replace my fluidmaster again. And of course to do that i need to shut off the water , but it wont shut off completly so water will still be running. What part should i replace to make the water turn off completely?

 

[havasu]

You will need pics on this one and know how to shut off the water main.

 

[frodo]

shut off the meter, replace the toilet inards/ ball cock

and replace the valve with new valve

 

[ihatefluidmaster]

You will need pics on this one and know how to shut off the water main.

 

[havasu]

That is a very simple replacement, however you first need to know how to shut off the water to the house. Do you know where this valve is located?