If you try many way, can't finish.
1、reinstall android studio : remove all
2、delete all
c:\user\your user name\.gradle
c:\user\your user name\.AndroidStudio2.0
3、reinstall android stuido
be careful path and directory, C:\Program Files\Android check this directory, have other Android Studio, likfe Android Studio1..... If have delete Android Studio1 directory, only keep Android Studio.