I have problem while creating VPN connection on win 8.1 64 bit with error "Unavailable - device missing".  I have try to uninstall and reinstall the device driver many times but still got failed until entering to this forum.

Please help and thanks for any answers here.

Hi Golek Upo,

Can we create VPN connection before? Have you checked the device manager for corrupted drivers? Have you installed any third party VPN software?
Here is a similar symptom for reference:
VPN not working - Missing device
https://social.technet.microsoft.com/Forums/windows/en-US/df23faf4-2811-47cd-ae33-f433ed6f3fbd/vpn-not-working-missing-device?forum=w8itpronetworking

We could try Kaspar Frederiksen`s suggestion to have a check.
As Ozsi posted, we could run the antivirus software to have a diagnostic to ensure the safety of the system.
To troubleshoot whether there is a third party conflict issue, we could perform a clean boot to have a check.
How to perform a clean boot in Windows
https://support.microsoft.com/en-us/kb/929135

Best regards