How to format external Toshiba drive without erasing?

[asdf212]

IO have an external Toshiba drive that I added a few files onto on a windows computer now Im using my iMac and I want to format it so its not a 'read only' drive, HOwever I cant lose any of the files on the drive..?

 

[Intell]

It's read only because Macs don't have the ability to write to NTFS drives. You cannot format it without erasing it. That's the definition of formatting. You can try a third party NTFS driver that will allow your Mac to write to a NTFS drive like NTFS-3G or Tuxera NTFS.