Photos will not open

The following has helped some users in similar circumstances:

1 - force quit Photos.

2 - launch Photos with the Option key held down and create a new, test library.

3 - import a couple of photos into the test library and close and open it a couple of times.

4 - launch Photos with the Option key held down band select your primary library.

What happened directly before this problem first occurred? Did you just upgrade to Mojave?

Could you post the first 50 lines or so of the crash log you are getting (in the Photos quit unexpectedly ... panel)?

Does Photos start correctly, if you select the Photos icon in the Applications folder and hold down the options key ⌥ while double-clicking the Photos icon in Applications? Keep holding down the options key, until the library chooser dialog appears. Select to create a new library.

If you need to reinstall the system, you may see the system problem in the error message in the crash log. That was why I asked to see the first lines of the crash log.

But I am glad that you could fix the problem with the help of Apple Support.