Is your Photos Library stored in the Pictures folder on your internal drive, or did you use an external drive? An external drive must be formatted in either APFS format or Mac OS Extended (Journaled) format. Additionally, the drive can not have had Time Machine on it since it was formatted. The newest macOSs won't even allow a Library on a non-Mac formatted drive to open, since there is a chance of damaging the Photos database. See this:
Move your Photos library to save space on your Mac - Apple Support
Did you do a finder search, like this?

That works better than Spotlight searches. Also try searching for "Photos Library" (or different variations) since the ".photoslibrary" suffix or the name may have been altered.
What happens when you click on the Photos icon? If it doesn't know where your library is, it should open up with a new empty library. Is that what happens?
If you close Photos and option-click on the Photos icon, it should bring up a dialog that shows all the libraries it knows about.
Let us know....