ADB not responding. If you'd like to retry, then please manually kill "adb.exe" and click 'Restart'

ADB not responding. If you'd like to retry, then please manually kill "adb.exe" and click 'Restart'
Errors from ADB:
ddms: 'I:android-sdkplatform-toolsadb.exe,start-server' failed -- run manually if necessary

Try below steps:

Close the Eclipse if running
Go to the Android SDK platform-tools directory in Command Prompt
type adb kill-server (Eclipse should be closed before issuing these commands)
then type adb start-server
No error message is thrown while starting ADB server, then adb is started successfully.
Now you can start Eclipse again.