lost all my photos

That's how the cloud version of Lightroom works. It manages the local storage and automatically unloads the local copies when the originals have been transferred to the cloud and will dynamically download files when needed. If you want to keep local copies there is a preference to do that. You can also mark albums to retain their local downloaded copies if you need them for quick access or are expecting to not have internet access while editing. Better yet if you want your images to always stay local is to use Lightroom Classic instead of the cloud version.