If you have the original installation disc or a backup of the ISO file, this is the safest method.
: A genuine 25-character product key that matches your specific version (e.g., Home & Student, Professional Plus). Microsoft Learn Safe & Free Alternatives
Additionally, users with a valid Office 2010 product key can still install it from Microsoft’s defunct Digital River archives? No—Microsoft removed all download links in 2022. The only legitimate source would be an original installation DVD, which does not contain “extra quality” patches.
Instead of searching for "free" or "cracked" versions, which often contain malware or are illegal, consider these legitimate options: Install Office 2010 - Microsoft Support