Solution: Right click on IE. YOu can find “Run as Administator”. Click that. Now type your Sharepoint Central Admin URL
It will work……………
Or
1) Go to Control Panel
2) Here click on "System and security"
3) Now here under "Action Center" click " Change user account control settings"
4) Get the scroll bar to "never notify".
5) Click on OK.
6) Restart your system.
Now open the browser in "Run as administrator" mode. Browse to the create web application page and the button will be enabled.
