I personally use kdevelop since many years now. And despite of the fact that it is not the most stable, and can have some bugs, it remained my favorite free to use IDE. It automatically backup files every X seconds (that you can choose), and can restore them in case of crash. Since kdevelop 5 crashes become exceptional. In kdevelop 4 it could happen seldom.

Another nice thing with the version 5 is that the kdevelop team provides app images to download. So you don't need all the Qt/KDE awful layer to make it work. And this works on Linux, Windows and Mac the same way.

I hear a lot about QTCreator, especially on linux. For me it was crashing all the time, while trying to port over fluid sandbox to linux, but maybe it runs on your side?

But to solve your actual problem, please use git - its very great for source code files. Nowadays its highly important to use some sort of a version control system, even for private projects! Just because you never know when your IDE or operating system are crashing. Also doing manual or automatic backups are much slower and requires more space than git - because git stores the delta only.

To get git working, you just need a git command line - thats it. Its not that hard and it will help you prevent data losses in the future.

I've been using CLion and it's absolutely amazing. Even better than Visual Studio IMO. The code completion, refactoring, macros, etc. are all top notch and a huge time saver. However, data corruption and lost work can happen with any IDE, and the real solution is version control or a local backup solution (or both).