Hi @art137,
Sorry to hear about that. By default, when an image is uploaded, for example, a.jpg, WordPress will be saving as a-scaled.jpg. So Smush will be only resizing the a-scaled.jpg, the original image would be intact.
I’m afraid, there isn’t any one-step solution that we could suggest to recover in the free version of Smush as it entirely depends upon how the images are implemented on your website.
The easiest workaround would be to revert to an existing backup. If not, could you please open a support thread regarding this so that we could check and have a better idea about your issue to advise further regarding this:
https://www.ads-software.com/support/plugin/wp-smushit/#new-topic-0
Regards,
Nithin