Start Windows Explorer.
Tools | Folder Options, View tab. Untick Hide extensions for known file types.
Navigate to C:\windows\system32\drivers\etc
Then look for the file called simply HOSTS (no .txt or anything else). If you do not find this file then the hosts file is not the cause of your problem.
If you find HOSTS, right click it and select Rename. Rename it to anything other than HOSTS then restart your PC.