I tried to find an existing thread for this, no luck.
I can save/open files in graphical, but when I want to use text based, I cannot save/re-open the file. I have been copying the text out and saving it with Notepad, restoring the same way.
To confirm, the Graphical files (.rbg extension) are being saved and reopened properly, but the text-based ROBOTC files (.c extension) are not? Are there any error messages that appear when you attempt to save a text-based file, and does a new .c file get generated and saved when you attempt to save a program?
Also, where are the programs being saved to? Try saving the files to a different location (such as My Documents or the Desktop) to see if this changes the behavior of the save/open functionality.
So meanwhile, problem solved - there were other RobotC app icons that were created (I did an update to 4.3) and one of them opens in C mode and can open/save .c files. The first one I had will only operate in graphical mode.