Had a leak on wc cystern on intake pipe on ground floor.Turned of water outside on meter, went into loft and turned a small valve off at the bottom of large storage tank. Fixed cystern, turned water meter valve back on, went into loft and turned the bottom storage tank back on. Inow have cold in all toilets cysterns, kitchen and laundry room. But I have no water coming through hot pipes. I have tried blowing into the hot tap at top of house, and also tried to introduce cold water into the hot tap from the cold tap with a hose to clear any air blockage, but still it won't work.
I feel it is an air blockage and I wondered if it was in the immersion hot water tank in the airing cupboard or elsewhere. Any ideas please. I don't think I closed any other valves.

went into loft and turned the bottom storage tank back on.
What type of valve is that. Could it be a gate valve? When you turned it on did the handle ever stop turning or did it just keep turning and turning and turning?