Hello my friends - I hope someone can help me.

My problem - There is no cold water coming from my shower. There is hot water, but no cold. There is cold water coming from all the other taps in the house. The shower is a 'power' shower which has both cold + hot pipes feeding into the shower box.

Yesterday the water was cut off (The whole village had no water) - not sure whether this has anything to do with it?

A friend has mentioned that it could be a airlock?. Is this the problem?. and if so how do I solve it?

Thanks for your time and help.

"A friend has mentioned that it could be a airlock? .....Is this the problem? ...and if so how do I solve it?"
More then likely this caused your problem.
"Yesterday the water was cut off (The whole village had no water)"

One of the first things I ask is, " Has the utility company done any work lately?"

What happens is that when they open up the water main to work on it dirtand soil falls in the open pipe. If it's in the main outside your house it will get pulled into your system and clog up the first valve that you turn on. In this case your shower. To fix this you'll have to shut the water off and open up the valve. Check the inlet ports of the cartridge for trash and dirt. Now turn on the cold water while the valve's still open and flush out the cold water supply. You might also want to flush,(not drain) your water heater. If you have dirt in your shower valve you also have it in your water heater. Good luck, tom