Missing Transferred Files from another Computer through HDD

JPalafox

Prominent
Jul 1, 2017
16
0
510
I connected my HDD 1tb on my friend's computer and copied large files e.g. iso, mov., rar, etc. taking up 1tb meaning the HDD is full of 1tb files.
Now when I returned to my PC and connected my HDD, all files went missing and the space they are taking up is also not registered meaning it went back to it's previous space before I copied files from my friend's pc

Now when I tried to transfer new files from an external drive on my pc to my HDD it said no more space but the file explorer shows a 700gb free space.

What could be the problem? and the solution?

Thank you so much