You say the problem only just began. What has happened to Photoshop in between it working and not, ie, any upgrades, updates, installs, etc? This will no doubt reveal the answer to your conundrum. Get PS to check for updates then do them all, especially any referencing Camera RAW updates.
The next thing you will want to check is that the image files are ok. Download the latest Canon image viewer from here
. You can also download the drivers directly from the canon site
. Just click the link at the bottom of the page.
All the best