Is the system version show below your post still valid? macOS 10.13? Or have you already upgraded to Catalina ?
You may want to test, if Photos is able to run at all, if you launch it directly from the Applications folder. This will ensure, that you are not using an old alias in the Dock or on the Desktop, that is incorrectly linked.
- Open the folder Applications and double click the Photos.app there. Does it launch this way?
- If not, hold down the options key ⌥ while you double click the Photos.app in Applications.
- Release the options key when the library chooser dialog appears and select to create a new library. Test a bit with the new library by importing a few photos. Does that work?
- If yes, quit Photos again, then try again to double click the library.
If Photos is working on anew library, but not on your main library, make sure, the new library is in a suitable location. It must not be on a network volume or a volume, that has been used for Time Machine backups and it must not be in a synced folder (Dropbox, iCloud Drive, Google Drive).