I disconnected the external USB hard disc, which had been functioning normally up to now, after cancelling a backup. On next booting the computer I got the message that a USB device was not recognised which I have traced to the USB hard drive. I have checked all the connections, removed the wires from the computer and reconnected them but still no recognition. Is there a way in which I can get the computer to "see" the hard drive?
From what you have said, you removed the External Hard Drive without going through the "Remove Hardware" procedure. There is then a chance that Windows was accessing the Drive when you disconnected it.
In all likelihood, the Drive is now dead. Others may know how to recover from such a disaster, although all that I have been told suggests that such an action will usually prove fatal.
I managed to find out that the HD was working although not being "seen" by the computer. I saw another article while looking for something else which referred to the Disc management function. Having typed in "diskmgmt.msc" I then saw in the lower panel the disc I was looking for. I then followed the instructions for setting it up and formatting and "Bingo" the disc appeared under "Computer"