Project not showing cocos2dx library in code

hi everyone, i have been working on a project and faced a strange problem where my project in not showing any functionality of cocos2dx where as all ,y other projects are working fine. i also tried to shift class and resources to other project but after using these classes and resources project start giving errors like undeclared or unknown … etc.
I reviewed my code 2-3 times and found no specific error that can cause this. At last i found this forum that may help me to find out the issue , thanks.

Have you changed any folders ( names/ positions)?

No, I am just replacing classes and resources.