Recently my 4TB exFat external USB Hard Drive (HDD) turned RAW, most likely due to not safely removing or some sort of corruption. I spent hours trying to get it back without having to recover each file. Both Windows and Linux could not read it, the drive appeared to be unformatted (no filesystem). Here's how I quickly fixed it and was able to get back all my data and use of the drive within minutes.
Boot a Ubuntu desktop (you can use a Live CD if you don't have one installed), open up the program called 'Disk Utility' and note the drive location (ex. /dev/sdb) of the affected drive.
Launch the app/program called 'Terminal' and type sudo exfatfsck <drivelocation> which should look something like this: "sudo exfatfsck /dev/sdb"
Normally this will fix it (has in the past for me), however this time I got the error "ERROR: invalid VBR checksum 0x7d00716 (expected 0xc069f9f)."
So, I connected the USB drive to a Mac Desktop/Laptop. Opened up the program/app called 'Terminal' and typed Typed "diskutil list" and hit enter.
Saw that my 4TB HDD was /dev/disk2, then typed "sudo fsck_exfat -d /dev/disk2" and hit enter.
Saw a bunch of lines scroll by and waited to see a prompt that asked me to "update?", so I typed "y" and hit enter. Once it was done, I exited and unplugged the device. Went back to my machine, plugged it in and saw that I was able to see all the data again like nothing happened!!
Hope this helps someone.
If you have NTFS or FAT, you can try "sudo fsck /dev/sdb" in Linux to see if it fixes the issue for you.
All credit goes to /u/bgdawes on reddit, in this post.
Note: I take no responsibility for data loss. I tried soo many things including free software such as TestDisk, MiniTool Partition Wizard and AOMEI Partition Assistant Standard Edition. This is what did it for me and was the fastest and easiest by far.
