Clicking My western digital starts clicking when plugged into the mains. The pc cannot detect it. Does anybody know how to fix this and can I recover the data. Thank you in advance for you time and help. Jon.

Is it a constant clicking?
If so it means your hard drive has departed this world for the next. I am sorry. I have heard this dreaded clicking many times myself. As for recovering the data there is a chance. In the 8 or 9 drives that have died I have recovered data from 5 of them. This is possible because more often then not the damage to the drive occurs on the circuit board rather then inside the drive. To fix this you will need to get an exact match to the board on your drive now.
You need to match both the model # and the DCM # of the drive.
The best places are computer stores that have a large supply of OEM drives. This can be expensive though. You can also check e-bay because I have seen hard drive boards only for as little as $15.
Once you have a board simply swap them out. You will know if it works right away.

Please remember this is not guaranteed to work.
There are also data recovery services, but they can be costly.
I hope this helps and good luck.