Hello NormanBolton ,
I hope you might be able to restore access to your data. What have you tried so far? It's a good idea to cover the basic stuff first. You should try using a different USB cable, different port on the PC and if possible test on different machine. It's also a good idea to run the manufacturer's diagnostics tool to check the drive. If that doesn't help a bit more information about your situation would be useful. If I understood correctly after you had a CRC error you were able to access your external for a while? Have you performed any changes to the drive recently? What OS are you running? What is the model of the external drive? When you say it's recognized by Windows, does that mean that the drive is displayed in My Computer or do you find it only in Disc Management?