Cannot mount external drive DiskManagement.disenter error 49221.

Hi Manic1015,

Welcome to Apple Support Communities. To help troubleshoot this behavior, we suggest to restart your Mac in safe mode. Once you're in safe mode, please restart your Mac as normal and test to see if you can mount the external hard drive without any issues.

If needed, here's how to restart your Mac in safe mode: How to use safe mode on your Mac

Best regards.

Do you have another commuter that this drive can mount to? Test if the drive still works with another computer.

If it does work on another computer, it may be best to drag the info off the drive to ensure it's protected.

Then, connect it back to the Mac, and format it properly. Connect to the other computer and put the data back on.

If it is not working properly on another computer, then there seems to be some corruption, and you will need to format the drive. If there is data to access, you will need to contact a data recovery service before formatting it, because formatting erases everything.

Erase and reformat a storage device in Disk Utility on Mac - Apple Support

Thanks.

See if this previous discussion is relevant.

NTFS external drives won't mount after se… - Apple Community