If you change any files such as the HOST file then be sure to back it up somewhere in case you need to revert back to it. It won't effect your OS though, and if you ever did anything that disastrous then you can always just roll back to a Windows restore point or back to factory settings if you...
Ransomware is not brilliant! Do you have any recovery points or snapshots you can revert back too? Hopefully you made backups of your files in which case reformat your HDD back to factory settings and go from there.