Alright so here the problem. I've started downloading Vermintide 2 yesterday. All was good I woke up this morning the download said around 47 Go / 56.9 Go I was happy. But I missclicked a Deathwing took the place of Vermintide 2 in the download section and I could put Vermintide 2 back. I rebooted steam and here was a surprise. Steam started to download Vermintide 2 all over again ! And there is more. I've deleted a lot of games off my hard drive yesterday to install Vermintide. I had free space. But when I relaunched the install it said that I doesn't have enough disk space but Vermintide 2 wasn't installed at all no files to be found. And here is where I need your help. Where are those ghost files that are taking up disk space ?
You could use something like WinDirStat to get an indication of things taking up chunks of space. It could be a partial download or something. Steam also allocates a bunch more space than the final installation size of a game, since it needs to unpack it.