If you previously had more photos in your Photos Library, you have to help Photos to find back to your main Photos Library.
Where have you been keeping your Photos Library? On an external volume or in your Pictures folder in your home folder? If you kept your Photos Library on an external drive, make sure, this drive is connected to your Mac.
- To get back to your main Photos Library, quit Photos, if it is running.
- Then hold down the options key ⌥ while launching Photos again.
- Keep holding down the options key firmly until you are seeing the library chooser dialog.
- Select the largest library from the list of photo libraries that will appear and open it.
Is there another Photos Library with more photos shown?
When you try to repair a library, Photos will always repair the library it has last opened by default. So your attempts to repair your library will have repaired the new, empty library.
To repair a different library, you have to select the library you want to repair in the Finder and double click it while holding down the key combination ⌥⌘. This way Photos will be launched using the selected library.
Are you really using this very old system version "macOS 10.13 High Sierra" or has a wrong system version been shown below your post?