I tried to re-install Ubuntu 14.04 LTS and I unknowingly checked on the option of Encrypt the new Ubuntu installation for security. Unfortunately I stopped the installation at midway, and then began to install Ubuntu without the encryption option. Nonetheless I think some files managed to get encrypted because my hard drive partition is not reporting all the memory there is: this partition is 991 GB, but the system tells me its capacity is 975 GB and that 925.5 GB are free. This doesn't make sense!
I used an external HDD to backup my important stuff and I (slow) formatted the partition. I am currently running Ubuntu with a live USB, so I don't really care about my files. What I am trying to solve is to delete the suspected encrypted files, so I can recover about 65 GB of lost/encrypted space. I still remember the pass-phrase I created, but i have no clue of what to do next; I haven't really do any encryption/decryption before. I am also new to Ubuntu, so there are some technical things which I'm not very familiar with.
I am posting a picture about the properties of the hard drive (notice the suspicious gray area on the pie): hard drive space
I am really open to suggestions in any case or if the problem doesn't have anything to do with encrypted files. Thanks in advance.