Okay, it looks like you posted this prior to me posting my comment above. I'm not familiar with this graphical utility, but I'm assuming that it means that your disk is visible (like, if you run ls /dev/sda, you see your disk).

So what you've probably got is a functioning hard drive, with a functioning partition table, and on the first partition (/dev/sda1), a LUKS layer.

I haven't used LUKS, but it's a block-level encryption layer for Linux. It'll have some command to expose an unencrypted layer, and you can mount that.

Let's try walking through this in a terminal.

From https://superuser.com/questions/1702871/how-to-do-cryptsetup-luksopen-and-mount-in-a-single-command, it looks like the way this works is that one runs:

$ sudo cryptsetup luksOpen <encrypted-device-name> <unencrypted-block-device-name>

Your encrypted partition name is presently at /dev/sda1. So try running:

$ sudo cryptsetup luksOpen /dev/sda1 my-unencrypted

That should prompt you for a password. If it can decrypt it, it looks like it creates a block device at /dev/mapper/my-unencrypted.

You can then create a directory to use as a mountpoint:

 $ sudo mkdir -p /mnt/my-mount-point

And try mounting it (assuming that it's just a filesystem):

$ sudo mount /dev/mapper/my-unencrypted /mnt/my-mount-point