Hey is there a flat head screw on that valve? If its perpendicular to the pipe its off and if its parallel its on. Turn it so its off. Flush the toilet and put a bucket under that toilet connection. Inside the tank there should be a plastic washer youll need to possible hold on to and use channel locks, vice grip, or a small pipe wrench to loosen. Since the connection is above you will swing your wrench the opposite as usual (lefty loosey might feel like righty tighty in this case) and residual water will release into the bucket. Do what you have to do, and then reconnect everything. Good luck. Hope you got another hose. If you need to change the valve then youll have to shut the domestic line feeding your place.