If you are trying to open a .7z file you have already downloaded, you will need a file archiver like 7-Zip , which is a free, open-source tool for Windows.
: Download the official installer from the 7-Zip website or the Microsoft Store .
: Always scan downloaded archives with antivirus software (like Windows Defender or Trend Micro ) before opening them, especially if they came from an unknown "useful post".
Are you having it, or are you looking for a link to download it?