I can not open photos

If all else fails try the following in order as needed:

1 - as a test launch Photos with the Option key held down and create a new, test library.  Import some photos and test to see if the same problem persists. Does it? This tells us if the problem is limited to your current library or is more wide spread. Then try opening the problem library.

2 - boot into Safe Mode according to Start up your Mac in safe mode - Apple Support and see if the problem persists. Reboot normally and test again.

NOTE: Safe Mode boot can take up to 10 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

Where do you keep the Photos Library? Have you checked, if it is still where it used to be?

• if you do not change anything and move your library, Photos will create a system photos library in the folder Pictures in your user home folder. Is this library still there? If yes, what is the file size?
• If you moved the Photos Library to an external volume to safe storage on your Mac, check, if the library is still there, where you moved it to.

If you can find your Photos Library, quit Photos, if it is running, then double click the library to open it in Photos. Can Photos open the library you have found?

Have you just upgraded to Big Sur?

If so from which version?

Has photos been working on Big Sur at all?

Have you been using photos previously? If so - when, on which version of Macos, and aprox how many photos do you have?

Did you figure this out? I cannot find the library either. I am wholly unimpressed with all the bugs Big Sur has on so many apps.

Try launching Photos with the option key held down and choosing your photos library from the dialog.