I primarily focus of Linux – though I recently came across this issue from a friends computer. Thought I might share the fix.
It’s a bit of an obscure issue, and I thought there weren’t enough well document guides on how to fix this, particularly for non-tech-savvy users.
It’s a relatively straight-forward procedure, it involves installing Hiren’s BootCD onto a USB Flash Drive, and booting into that to utilise one of it’s Disk Partitioning tools.
Issue
When in the Disk Management Tool, the “Extend Volume” option on the C: or Windows Boot Partition is greyed out. This is because there is another partition directly to the right of the partition you wish to extend, most likely the Windows Recovery Partition.
Caution
When fiddling with partitions, or your storage mediums configuration, it is imperative that you take backups of your data before committing changes. How valuable is your data to you? You should take a moment now before you proceed by taking a backup of your files in-case things go pear-shaped. External Hard Drives are very cheap and you should consider taking a backup of your files now more than ever.
Please pay attention to any prompt’s and warning messages. Read through this post completely now before attempting the resolution procedure. If you run into anything unexpected, search for something online first before guessing.
Resolution
To resolve this, we must move the adjacent partition further across to the right, and create “Unallocated” space to the right of the partition you wish to extend.
Download Hiren’s BootCD (HBCD). The download link should be near to the bottom of the page, supplied with ISO Checksum Value’s. You can use these to verify your copy of HBCD if you wish. HBCD is a copy of Windows with recovery tools pre-installed, and is free to use for non-enterprise users.
Download Hiren’s BootCD PE – ISO2USB. This tool will allow you to burn the HBCD ISO to a USB Flash Drive. Follow the procedure on the “USB Booting” to do this. This will require to you source a USB Flash Drive at least 8GB in size.
Open ISO2USB and use this tool to write the HBCD to your USB Drive.
Once you’ve burnt a HBCD to your USB Drive, reboot your computer and select to boot from the USB flash drive, rather than Windows 10. This may be tricky in some circumstances, particularly for users who have never booted from a USB Flash Drive before. Generally, this involves starting your computer into your BIOS settings. There are a couple guides online for how to do this, such as this one. Otherwise, you can just search for one online.
Once you’ve booted into HBCD, open the Start Menu and go to All Programs > Hard Disk Tools > Partition Tools > Macrorit Partition Expert.
Have a look at your disks and locate the “C:” partition. This is usually indicated with as “C: (NTFS) Primary”. This is the drive you wish to expand into “Unallocated” space. Directly to the right of this, there should be another partition in the way. In my case, Windows Recovery. We need to move this partition to the right.
Right click the partition that is in the way, and select “Resize/Move Volume”.
When a new window appears, under “Size and Location”, there should be a horizontal bar graph representing the disk space this partition occupies. Drag this partition all the way to the right of this graph. Do not resize it. You should see the diagram of all the partitions update on the bottom of this new window. Then, click “OK”
Now we can expand our Windows Boot Partition (C: Drive). Right click the Windows Boot Partition and select “Resize/Move Volume”. A new window should appear.
With the partition, we are going to use the graph at the top of the new window to drag the partitions right-edge all the way to the right, to occupy all the remaining disk space. Now click “OK”.
Once this is done, we can click the “Commit” button at the top left of Macrorit Partition Expert. This will write our changes to disk.
Shutdown and restart your computer. I’ve found at times just rebooting causes Windows to freak out. Click the Start Menu and then Shutdown, then turn your computer back on.
Boot back into Windows (not HBCD), and see if your “C:” Drive has increased. If not, have a look at the Windows Disk Management tool, or boot back into HBCD and check Macrorit Partition Expert again to see if your changes have been saved.