The "unity 3d button does not work" error can be caused by a multitude of factors, each depending on the specific context in which you're encountering it. Here are some common causes:
Incorrect Event System: Unity utilizes an event system to handle UI interactions. If there isn't an active Event System object in your scene, or if it's configured incorrectly, buttons may not respond to clicks.
Button Component: The button might not have a Button component attached to it, or the OnClick() event in the Button component might not be set up correctly.
Scripting Errors: There could be issues with the function that is being called when the button is clicked. This could be due to syntax errors, logic issues, or other related problems within the script.
Layer and Order Settings: The button might be hidden behind other UI elements, blocking the interaction. Also, possible misconfiguration of layers and order in layer settings of UI element could cause such an issue.
Canvas Group Component: If there's a Canvas Group component affecting the button and 'Interactable' is unselected, this would make the button unresponsive.
Solution - Here's How To Resolve It
Depending upon the root cause, here are some potential solutions:
Validate Event System: Ensure there is an Event System present in your scene. It usually gets added automatically when creating a UI element but check for its existence and proper configuration.
Check Button Component: Make sure the button has a Button component attached to it. Verify the OnClick() event is set up to call the desired function when clicked.
Review Your Script: Debug your script to ensure there are no exceptions or logical errors preventing the function from executing. Check for any compiler errors in the Unity console and fix them.
Inspect Layer and Order Settings: Make sure the button is not placed behind other UI elements. Ensure that the button's layer isn't blocked by the camera's culling mask. Validate order in layer settings of UI element.
Check Canvas Group Settings: If a Canvas Group component is present, ensure 'Interactable' is selected so the button can respond to user input.