I would download a data recovery software programme if the data is important, you can get some f these as shareware or free if you look around. As long as the computer can recognise the drive, you will be able to get the data back
As to why it is appearing as not formatted could be down to a number of reasons, commonly, transferring a usb drive to a mac and back causes these issues, or, the drive may be failing
Answers & Comments
I would download a data recovery software programme if the data is important, you can get some f these as shareware or free if you look around.
As long as the computer can recognise the drive, you will be able to get the data back
As to why it is appearing as not formatted could be down to a number of reasons, commonly, transferring a usb drive to a mac and back causes these issues, or, the drive may be failing