| You will have to shut off the water to the house and replace the toilet stop valve.
Does your stop valve look like the one below? If so purchase a new one, Its called a 1/2" to 3/8" compression angle stop valve. Turn off the water to the house. Open a faucet to relieve the water pressure. With two adjustable wrenchs, one to hold the valve with and one to loosen the nut, remove the old valve. The nut will turn clockwise as you look at it. Install the new valve using the old nut and compression ring. Then you can turn off the water at the toilet to replace the tank bolts. Be carefull doing that because you can easily break the tank if you tighten them too much. | 
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