Replace image from my library is not working

Sorry to hear about your difficulties. Typically when you select an element, you should get a box around it with a bar and some additional options including replace. I try these and see if they help:
- Try clicking the blank photo in the canvas to see if you can select it

- Can you add another photo over the top of this one?

- Does creating a duplicate of the project and working in that instance make any difference?
- Try clearing the browser cache  -  https://adobe.ly/3MPJpg1

- Test in incognito/private browsing mode -  https://adobe.ly/4gg8JJI

Hope these help,
Dave