ping is not recognized as an internal or external command

This error may occur due to messed computer path.To resolve the problem:

1. Open a Command Prompt and type: Set .
2. You should see included: Path C:\WINDOWS\system32.
3. To correct the path, on your system go to Start>right-click My Computer>click Properties.
4. Click the Advance tab.
5. Click the Environment Variables button, and select the Path variable listed under System Variables.
6. When editing it should include: %SystemRoot%\system32.
7. Which translates to something like: C:\WINDOWS\system32.
8. Each entry included in the path must be separated by a semicolon.
9. Try executing the Ping/Telnet command now from the command prompt.
10. The same will also work for Telnet and other commands.