Try to narrow down the problem. How to trouble shoot "Photos keeps crashing or hanging" on iMac running High Sierra
Test with a new , empty Photos Library, to see, if the problem is caused by a library corruption or incompatible items in the Photos Library. Create additional photo libraries in Photos on Mac - Apple Support
If even a new, empty library dies not work, test in a different user account, for example as the guest user: Isolating an issue by using another user account
If the problem only happens in your current library, check if the library is stored on a compatible drive, or if you are running out of storage. (Where is it safe to store a Photos Library? Requirements for the external drive)
IF not even a new library is working, but you can work with photos in a new user account, try to fix the permissions on your user account: Resolve issues caused by changing the permissions of items in your home folder - Apple Support
If the problem is system wide and even happens in the guest account, reinstall Mojave by booting into the recovery partition. Just install the system again on top of the current system. You do not need to do a clean install. See: OS X: About OS X Recovery
Photos is part of the system and cannot be reinstalled separately. To reinstall Photos, you need to reinstall the system.