How Do I Add Date Taken to a Photo in Windows?
Windows can edit a photo's date by hand, one file at a time. For a library you need a tool that does it in bulk.
Right-click the photo, choose Properties, then Details. Click beside Date Taken and type a date. Windows saves it into the file. That is the manual way, and it works.
It also takes about twenty seconds per photo. For two thousand photos that is eleven hours of typing, and you have to know the right date for each one before you start.
Takeout JSON Metadata Fixer gets the dates from your Takeout .json files, or from the photo's own hidden data, and writes them in for the whole folder at once. It runs on your own computer and is free for your first 500 photos.