How to restart a emulator or android mobile device using adb tool via command prompt

sometimes, emulator or device get connection disconnected from eclipse to emulator/device.
that time also, its very useful to detect emulator or device again in eclipse using adb(android device bridge).

D:\Android\android-sdk\platform-tools>adb.exe kill-server

D:\Android\android-sdk\platform-tools>adb.exe start-server
* daemon not running. starting it now on port 5037 *
* daemon started successfully *

D:\Android\android-sdk\platform-tools>