If you go to your android-sdk/tools
folder I think you'll find a message :
The adb tool has moved to platform-tools/
If you don't see this directory in your SDK, launch the SDK and AVD Manager (execute the android tool) and install "Android SDK Platform-tools"
Please also update your PATH environment variable to include the platform-tools/ directory, so you can execute adb from any location.
So you should also add C:/android-sdk/platform-tools
to you environment path. Also after you modify the PATH
variable make sure that you start a new CommandPrompt
window.