Hello there AtaritaStott,
Can you see the drive in Disk Management or Device Manager? If yes, I would suggest you to run chkdsk (drive letter): /F in the Command Prompt. The cause of your issue might be a file system error, so this command may fix it.
If this does not help, there is a chance that the TV formatted your drive. In this case, you should reformat the drive. Just keep in mind that you will lose your data in the process.
Hope this will help,
D_Know_WD