Can't mount exfat external hard disk drive: "Volume was not properly unmounted."

I can't mount my HDD anymore. After the last time I used it, I clicked "**Remove safely**" in my file browser, and now I can't read data on it anymore. Here are some diagnostic commands I executed:

`
# fdisk -l
Disk /dev/sdb: 465.73 GiB, 500074283008 bytes, 976707584 sectors
Disk model: Elements 10A8
Units: sectors of 1 × 512 = 512 bytes
Sector size (logical / physical): 512 bytes / 512 bytes
I/O size (minimum / optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0xf2c19c1e

Device     Boot Start       End   Sectors   Size  Id Type
/dev/sdb1        256  976707583  976707328  465.7G  7 HPFS/NTFS/exFAT

` # fsck.exfat /dev/sdb1 exfatprogs version : 1.2.2 too long label. 139 failed to read volume label invalid start cluster of allocate bitmap. 0x34c04c90 failed to read bitmap failed to verify root directory. /dev/sdb1: clean. directories 1, files 0 --- # mount /dev/sdb1 /media/myself/Medias/ mount: /media/myself/Medias: can't read superblock at address /dev/sdb1. dmesg(1) may have more information after failed mount system call. --- Here are the messages seen in dmesg when attempting the previous mount command:

`
[ 1439.474346] exFAT-fs (sdb1): Volume was not properly unmounted. Some data may be corrupt. Please run fsck.
[ 1439.516358] exFAT-fs (sdb1): failed to read sector(0xd57a397000)
[ 1439.516365] exFAT-fs (sdb1): failed to load upcase table
[ 1439.516367] exFAT-fs (sdb1): failed to recognize exfat type

` I'm trying TestDisk to analyze/repair my HDD, but how can I repair my HDD? I have no issues booting into my system, this question is about **repairing an external drive**, used for data storage.