You can re-link the photos, but you have to do this for every photo.
btw: Why do you care about the file names? I don't see why you changed these file names in the first place.
Basic rule: Perform file manipulations only from within LR, except you know exactly what you do.
Outside Lightroom, change the file names back to what they were. That's the easiest way to correct things. And in future, do any renaming in Lightroom (but you've already learnt that lesson, I hope).
Do you have Bridge? Its file renaming feature allows you to search for C_04 and replace it with C_05 - it's called "string substitution" in Bridge's renaming dialog.
Thank you. I was looking for such a reference link!
As to your btw, it's the system I use! It's important that the filenames are unique and sequential for my system, so it would be a nonsense to have two files with the same name.
Thanks, I'll have to consider which is the easier option of the two suggested!
Unfortunately, I don't have Bridge, but yes, lesson learned! :-(
Regarding your system:
I also have unique filenames. I let LR generate a unique filename upon import/copy and never have to worry about it.