Done building project "Project.vcxproj" -- FAILED

Question

I wrote some lines of code to simply read and write an image and it was working a few days ago, but now Visual Studio gives these errors: "1>Done building project "Lab1_PI.vcxproj" -- FAILED." and it says it was "unable to start the program" and that the system cannot find the file specified.

I also tried to add add _CRT_SECURE_NO_DEPRECATE and _CRT_SECURE_NO_WARNINGS via right-click project->C/C+±>Preprocessor->Preprocessor Definitions, but nothing changed.

Also, here's my code, but it is correct since it was working a few days ago:

#include <iostream>
#include <string>

#include "opencv2\core.hpp"
#include "opencv2\highgui\highgui.hpp"
#include "opencv2\imgproc\imgproc.hpp"
using namespace cv;
using namespace std;

int main(int arc, const char** argv) {
   string imgPath = argv[1];
   string img2Path = argv[2];

   cv::Mat  img = imread(imgPath);

   if (!img.data) {
       cout << "error:no image" << endl;
       return -1;
   }

   imshow("flower image (color)", img);

   Mat img2;
   cvtColor(img, img2, COLOR_RGB2GRAY);

   imwrite(img2Path, img2);

   imshow("flower image (grey)", img2);

   waitKey(0);

}

I would be really grateful if someone could help me fix this problem because it stops me from using Visual Studio and I really need it for a project!