ragz4u wrote:He suggested that if we could find the exact clone of the hard disk, he could replace the PCB
As I said before, if all you want is the PCB then post in the Hard Drive Market section (and search the forum for PCB vendors). I am not sure that you are dealing with a data recovery specialist, as they would probably be able to find a replacement PCB better than you can find one. Are you confident in your choice of repairer? Are they really a data recovery specialist (especially since you say the data is important to you)?
Also there are other possible causes for a hard disk not to be "detected", not only a faulty PCB. Unfortunately, your comment about it not being detected is ambiguous - do you mean it was not detected by the BIOS? Or Windows disk management? Or Windows (My) Computer? Or somewhere else? At the start of the problem, before you took the disk to the repairer, did the disk spin when power was applied? If so, did it then stay spinning? Did it make any unusual clicking sounds?