(Recommended) 

NOTE: This example uses the file “hosts” as an example but other files can also be modified using this technique.
If at some point you need to modify your hosts file in Windows 7, you’ll most likely have to change your access rights to that specific file.
Please note that you have to have administrator privileges to make the following changes.
  1. In Explorer, go to the file you wish to Edit. In this case “c:\windows\system32\drivers\etc\hosts”
  2. Right-click on that file and select “Properties”
  3. Select the “Security” tab
  4. Select your Users.
  5. Click on “Edit”
  6. Click on your username again and modify the permissions as you wish. In most cases, you can give yourself “Full Control”
Picture of Changing file permissions for a file in Windows 7
Changing file permissions for a file in Windows 7