How do I open a built game in Unity,How do you open a built game in Unity?

Okay so heres the problem, im making a game and im writing a script but i cant remember how to doa certain thing but I remembered that i made a script that does exactly what i need. The issue is that the unity project with the script is on my old computer that there is no possible way to access. But i do have a build of that game that has the script. So my question is, is it possible to open up and look through the assets and scripts of a built Unity game? Or is that impossible? If it is then let me explain my script issue. I need to know how to enable and disable child game objects with a script. I have a cube with a box collider trigger on the hand of my player and i want to be able to enable the box with the box collider game object when an attack animation is playing and disable the box when an attack animation is not playing. The enemy takes damage just from being next to me because the box collider trigger is always on but I only want them to take damage if im actually attacking them. So how do you disable and enable a game object in a script?,Ok so heres the problem. Im making a game and im having an issue trying to make a script do a certain thing but I can’t remember how to do it (enable and disable a child game object with a script) but then I remembered i made a script that did exactly this. The problem is that script was on my old computer that i have no way of accessing, however i have a build of the finished game that contains the script i want, but i no longer have the unity project file for that game. So my question is, is there any way to open up and look through the assets and scripts of a built and exported Unity game? Or is that script just gone now? And if it is, could you tell me how to enable and disable a child game object. If you need context, i have a cube with a box colider on the hand of my player and i want to enable the cube game object when I attack and disable it if im not doing an attack animation.