If there is data on the drive, do not format the drive! Formatting the drive will delete all of the data from the drive.
When running the CHKDSK command, if error The type of file system is RAW CHKDSK is not available for RAW drives appears, this typically is an issue with Windows 7 or above. In this scenario, booting the computer using a Windows Operating System prior to Windows 7, or a Linux Operating System might be required in order to access the filesystem on the drive and recover the data.