how to block a site on a computer

1.go to system32>drivers>etc>host .open it in notepad
2.in the end: write:
127.0.0.1 {hit tab}
*www.sitename.com*{hit enter}
127.0.0.1 {hit tab}
*sitename.com*
and save
open run type
ipconfig /flushdns


If you find that the contents of the hosts file are not being picked up by Windows it might be because the file is corrupted though the corruption is not evident in your editor. The best thing to do is to delete or move that file and create a brand new hosts file and hopefully the contents of this hosts file will be picked up by Windows.