Aspect ratio changes from Library to Develop module

Do you have 1:1 crop set in your camera.

"when I choose the Develop module, the image is cropped to 1:1 and I cannot resize to retrieve the pixels. When I go back to the Library module it remains 1:1 and I have lost the original aspect ratio"

Perhaps you have somehow set a raw default that sets the crop to 1:1.   Go to Preferences > Presets and make sure Override Global Setting For Specific Cameras is unchecked:

Are you able to reset the photo using the button in the right column (at the bottom)? Did you update recently to 11.4.1? Does this happen on every image in your catalog?