no hot water after trying to remove air lock

this will only work if cold is off of the main,if you cant shift it have you tried washing up liquid squeezed into cold feed to cylinder it breaks the surface tension in the pipe and has allways worked for me,if not get a qualified plumber in to sort it for you.you also may have pushed muck from tank into pipework and caused a blockage.

Try by going to the kitchen sink, open both hot & mains and push your hand over the tap and that will allow the mains pressure to fly up the hot to get the airlock/blockage out. I do it for a few mins and always works for me.