Dig up those original CDs or backups. If you have a valid product key (usually 5-part alphanumeric), reinstall from original media. Some online archives host ISO images of original VFP 9.0 CDs (legal only if you own a license).
This is the most "official" route. If you or your company has an active Microsoft Visual Studio subscription, you can often find VFP9 in the "Downloads" or "Legacy" section.