Welcome to Tom's Hardware, @Ballerina!
I'm sorry to hear about your issues with the WD My Book external drive. I'd recommend you try swapping the USB cable of the external with a different one and also check if you would be able to transfer photos to the drive from another computer. Another thing I'd advise you to do is to backup all your data from the My Book somewhere else by copying it there, until you are finished with the troubleshooting. This is the surest way to avoid any potential data loss.
Once you have your data from the external hard drive copied to another storage location, attempt to
reformat the drive through Disk Management and then copy those files back. Afterwards, check if you would be able to copy photos/media files to the HDD again.
Keep me posted with the troubleshooting and let me know if you have more questions!
SuperSoph_WD