[Talyrius]

Assuming you're running Windows 8 (x64), do the following for 7-Zip:

1. Visit 7-Zip's website to download and install the newest version.
   
   
   
2. Open Search (Win+Q) and look for "7-Zip." Right-click on 7-Zip File Manager and select Run as administrator.
   
   
   
3. With the 7-Zip File Manager now open, click Tools and then Options.
   
   
   
4. On the System tab, click the + button on the column (User or All Users) you'd like 7-Zip to associate files with. If another application is already associated with that file type, you can click it to reassociate it with 7-Zip. Alternatively, you can click the + button again to let 7-Zip reassociate with all file types it supports.