Resolve WordPress Cart Issue

My WooCommerce store suddenly stopped letting customers add anything to the cart. No matter which product they click, every page behaves the same: they press “Add to cart” and nothing at all happens, so the cart remains empty and checkout is impossible.

Here’s what I already know:
• The symptom shows on every product page, desktop and mobile alike.
• Items never reach the cart—there’s no success notice, no error, just silence.

I need someone to trace the root cause (theme, plugin conflict, AJAX, caching, JavaScript, or anything server-side) and implement a solid fix so:

1. Products can be added instantly and reliably.
2. The cart updates visually after each addition.
3. Checkout proceeds through payment as normal.

Please test your solution end-to-end before handing it over and let me know exactly what you changed, so I can keep the store stable with future updates.