Diskmgmt shows the increased space .However the drive is not showing as extended

Extended Disks Remain Wrong Size

• Issue:

What’s wrong with this picture?

• Spotted it yet?
  
  Yes, that's right.  The Data (D:) Properties dialogue does not tie up with the details shown in Disk Management.  Disk Management shows the partition as 80GB whereas the properties show it as only 10GB in capacity.
  
  

• Problem Faced while extending disk:
  
  

  

  
  

  
  

  
  

• I had extended the G drive here as per the request. It has completed successfully on diskpart cmd with an error shown below and also the diskmgmt shows the increased space .However the drive is not showing as extended in windows explorer.

• error message during the partition expansion:

 

• Solution:

KB832316 - The partition size is extended, but the file system remains the original size when you extend an NTFS volume

• The stated cause being "This problem occurs because the NTFS driver exhausts its resources when it tries to extend the volume."
  
  

The KB also details how to fix.  But I'll include the four step fix that worked for me here too:
Open an administrative Command Prompt (Right click "Command Prompt" and select "Run as Administrator") and Run Diskpart

• At the DISKPART> prompt, enter list volume 
• select volume # (where # is the number of the incorrect volume) 
• extend filesystem  
• Now the file system size should match the extended partition size: 

•  Now the file system size should match the extended partition size: 

For more details refer: https://support.microsoft.com/en-us/kb/832316