Leaky shut off valve to toilet need to know what kind of sealant to use can't turn off Main water
Dry ice on the pipe to freeze it so you can replace the valve has worked for me in the past. Pack 2-3" of dry ice around the supply or main line if you can access the smaller line to the toilet 1" would work. Turn on a cold water tap after several minutes to relieve pressure and verify there is no water flow. Once pipe is frozen replace valve, remove dry ice and you will be good to go. Use gloves with dry ice or instant frost bite will ocour if handled with bare skin.