Telnet by default, is disabled in Windows 8. This is to protect an unsuspecting user from hacking attacks. But if you know what you are doing, and want to re-enable telnet, here is how to do it.
1. Open up Control Panel by clicking Computer shortcut icon on Desktop and clicking Control Panel on the top taskbar.
2. Open Programs and Features.
4. This will open another dialog box listing all of windows features. Scroll down till you find the option Telnet Client and Telnet Server. Tick check both of these options to enable telnet on Windows. It is important you check both of these to enable remote computer sharing.
5. This would continue with the installation process. In moments, Telnet should be installed and when done, you can click Close as shown below.