C++ programs unable to find header files

I’ve been using GATE for almost a year for generating simulations. However, I did not face this issue until now. Whenever I run my c++ file, it shows an error for all the root header files stating " No such file or directory found"
I checked the installation of the Root folder, it is present. The header files are also present in the include folder.
I’m not understanding the cause of the problem all of a sudden.

ROOT Version: Not Provided
Platform: Not Provided
Compiler: Not Provided

Does it say which file is missing? Which version of ROOT are you using? (And which one did you use before)?

The version is 6.18 It has always been the same version. It is showing file missing for any root header (TROOT.h, TSystem.h and others)

Is it possible that some of the involved paths contain “space characters” (or some “non-US-ASCII characters”) inside?