Change the hostname for Windows Server 2008:

1.1. Right-click the My Computer icon and choose Properties .
1.2. Select the Computer Name tab and click on the Change button.
1.3. Restart the server.

To change the hostname on Windows Server 2012 and newer:

1.1. Go to Control Panel > System > Change Settings > Change… and insert another Computer name (which should not contain more than 15 characters).
1.2 Restart the server.

For Plesk 11.0 and earlier: Use the Plesk command line tool ftpmng.exe as follows:

“%plesk_bin%\ftpmng.exe” –remove-all”%plesk_bin%\ftpmng.exe” –reconfigure-all

For Plesk 11.5 and Plesk 12 Use the utility repair.exe as follows:

“%plesk_cli%\repair.exe” –reconfigure-ftp-sites

For Plesk 12.5.30 and Plesk Onyx use repair utility: plesk repair ftp

By anup