Because there are several ways to do stuff with Time Machine, it's hard to say much without more information. When you say photos do you mean pictures, rather than the Photos app or the Photos Library?
Since this is the Community for the Photos app, you might mean that you are trying to get pictures back from a previous Photos Library-- is that it? If that's right, this note might help.
Time Machine Restores a Photos Library - Apple Community
The point there is that you don't restore pictures, you have to restore the entire Library. And you can't drag and drop. You may want to choose "Keep Both" rather than replace your original Library. This may require lots of room.
You didn't say, but is your Photos Library on your internal drive? An external drive, if not formatted for Mac, may cause lots of problems:
Move your Photos library to save space on your Mac - Apple Support
You also didn't say if you're using iCloud Photos, and if you are set to Optimize Photos. That may be helpful information.
As to the Photos app-- you don't restore the Photos app, it is part of the macOS.
For individual pictures, I would "Enter Time Machine," as well, and navigate to a date where the pictures might be, and restore those.