Sorry that the Canon 77D files are not opening in Photoshop. Could you please let us know which version of Photoshop are you using and do you get any error message when you open an image into Photoshop? The Canon 77D requires atleast camera raw version 9.10 to process raw images.
The 77D has been supported since April 2017 with Camera Raw 9.10. See here:
The current version of Photoshop is 19.1.6 with Camera Raw 10.5.
What specific versions of PS and CR are you using and what operating system does your computer have?