I have just changed two basin and two bath taps in the bathroom. Immediately after this I have not hot water in the whole house. I have played around with the walves etc, with no luck.
I cant see any leaks.
Probably an airlock in your hot water system. Some questions though. 1. Is there any water at all coming out of your hot taps? 2. Do you have a hot water cylinder? 3. If so, is it getting hot? The answers to these might help to determine where the airlock may be.
If the answer is yes to 1 & 2 but no to 3, then it's likely to be the heating coil inside the cylinder that's airlocked. If it's no to 1 but yes to 2 & 3, the airlock will most likely be in your hot water supply system between the cold water storage tank that tops up the cylinder and the outlet to the taps at the top of the cylinder. I'm assuming here that your cold water tank has refilled properly after re-instating the system following the tap changes.
To clear a coil airlock, first ensure that your boiler is off then locate two pipes one above the other on one side of your cylinder. Slacken (but do not remove) the fitting that connects the higher of these to the cylinder. The head of water in your CH top-up tank should then push out any air followed by dribbling water in the same way as bleeding a radiator. Once water comes out without any air bubbles, resecure the connection. Alternatively, if there is a radiator type bleed valve on the top one of these two pipes, simply open that to let the air out.
To clear an airlock in the main body of the cylinder, ie if no water at all comes out of the hot taps, try coupling a hose across from the cold tap to the hot one on your kitchen sink then open the hot tap followed by the cold one. If you have a mixer tap on the sink, simply press your thumb over the outlet and open the taps in the same order. The mains pressure in the cold water should then push the air back up to your cold water storage tank.
If, however, you have a Combi boiler or instant water heater please re-post that information as there are other forum members who may be able to help.