No water from hot water taps.

If you smother a mixer tap spout, open up the side/ lever which has no water coming through,then slowly open up the lever which has the water coming through. keeping your hand firmly on the tap spout at all times. hold this for around three min if possible. you will force the air pocket out of the system. Hope this helps

From your description it sounds like you have an "air lock" An air lock like the name implies is when air is introduced into your pipe works causing a blockage that may be partial or complete. This can be experienced in both mains water supply pipes and central heating pipe work(although the two never mix) There are three methods to address this, two of which you can probably do yourself and a third if all else fails needs to be done by a tradesman. Method 1. Applies to single mixer tapes Cover the tap water outlet. Open the hot tap first! Then open the cold tap. Both fully opened. The cold water not being able to find its normal route will reroute via the hot pipe hopefully forcing out the air lock. Method 2. Applies to separate hot and cold taps. Connect a hose between the two taps. Turn on hot first then turn on the cold tap. Same principle like above applies removing airlock. Method 3. Trades only Drain down of system.

Airlocked

It depends what type of boiler you have. If it is a combi, you have left the filling loop open. If not a combi, you have an airlock. I would advise calling a plumber