project stops working if I modify anything

I am working on a project with my friend using the haar-tracker. basically particles come out of your eyes and nose and mouth. so I sent her some files and she sent me some so we would have the same code. Hers worked but mine doesnt show the particles although it’s the exact same project files.

So she sent me her whole file with everything in it and it worked on my computer UNTIL I changed something in the code and tried to run it. Then all the particles disappearedI changed it back but it still didn’t work.

This has happened to me before that the project has some sort of stored memory of the project but as soon as you try to change anything it stops working

It gives me no warnings or errors. Does anyone have any idea what this could be?

Oh I figured it out. I just had to rebuild the project (with the blue arrows) and it works fine.