normally i do it online, but to be shure if win 2012 recognize diskspace you should use diskpart to check if win recognize anything.
cmd -> diskpart -> list disk -> select disk 0 -> list partition
and give output
if not you should be careful
in addition i recognized that it is a simple volume and contains a 100mb non ntfs partition and system root might be possible that you cant solve this online because you cant convert it into dynamic disk.
my solution would be check the diskpart stuff and if you see free space at the end of the simple volume attach the disk to a other vm and try to grow it as a data volume or with a 3rd party disk tool.
make shure that there is no snapshot AND that you have a valid backup of your data!