Filesystem full but empty after corruption

I have a drive of 17 (18TB) which I know had a lot of files on it.

After corruption, i did a fsck on seid drive.

Now, when using df -h the result is the following:

/dev/sdk 17T 7.5T 8.1T 49% /mnt/drive5 however, when I cd into the drive, the drive is empty. No files on it. Just the lost+found folder.

user@hostname:~$ cd /mnt/drive5
user@hostname:/mnt/drive5$ ls
lost+found

going into that folder as root, this folder is empty

trying to do a fsck again, It says the drive is clean..

user@hostname:~$ sudo fsck.ext4 /dev/disk/by-uuid/e5d4ea17-a48d-4d8e-9bbb-5d50504aa49a
[sudo] password for user:
e2fsck 1.45.5 (07-Jan-2020)
/dev/disk/by-uuid/e5d4ea17-a48d-4d8e-9bbb-5d50504aa49a: clean, 11/274661376 files, 2025315608/4394582016 blocks
user@hostname:~$

Is there anyway to restore the file system?

Edit: Filesystem is ext4

You can try to use "TestDisk" to recover the filesystem. If that fails you can still try to recover some data using "photorec". It is considered good practice to work on a copy of the whole partition, because you can break things more while trying to repair. Might be impractical with a large partition though.

Edit: You say you use "ls" to check if there is anyting on the drive, try "la" or "ls -a" to be sure you dont miss any hidden files or folders when trying to figure out what takes up your disk space...