im trying to increase the size to 100GB, but its grey out in c drive disk management 

Increase the size in the VMs tab then reboot your VM, just shutdown won't work.

i did that, but it wont add in the C drive, i cant expand it, its grey out 

The problem is likely with the VM then, as that is the only things you need to do.

27 minutes ago, ren88 said:

i did that, but it wont add in the C drive, i cant expand it, its grey out 

While running the VM did you try using the Rescan Disks from the Action menu in Disk Management?    I have found in the past that this is necessary to get the extra space recognised.

i did that, but it only gives me shrink but the extended volume is still grey out 

1 hour ago, ren88 said:

i did that, but it only gives me shrink but the extended volume is still grey out 

Does it show the extra (unused) space is there.   If so there may be something about it that is stopping the expansion.

 

one thing that might be worth doing is creating a new gparted VM (using a gparted bootable ISO), and assign the vdisk to that to see if gparted can expand the partition.    If you try this I strongly recommend that you first backup the vdisk in case gparted does something that upsets the Windows VM.

2 hours ago, ren88 said:

i did that, but it only gives me shrink but the extended volume is still grey out 

Is there free space right to next to the partition you want to expand or is there a small partition next to it? (better yet post a screenshot of disk management)

Literally did this today, as johnnie said, make sure you've done a reboot of the VM after expanding.
Also make sure when changing disk size in unRAID that you press enter, not just change and click out, this looks like it commits the change, but it does not.

 

Note: I found after expanding I had ~25GB of previous windows install (that could be deleted) due to the newest major update.

If your running shy on space I'd take a look at 'disk cleanup' with 'clean up system files'

On 3/4/2018 at 2:57 AM, johnnie.black said:

Is there free space right to next to the partition you want to expand or is there a small partition next to it? (better yet post a screenshot of disk management)

here you go 

Like I mentioned you have a small 100MB partition on the right of the main partition, so you can't expand it, only create a new one.

If you attach a bootable image with partition management software to the VM, you could move the small partition to the end of the free space, and expand the main partition.

 

https://sourceforge.net/projects/gparted/files/gparted-live-stable/