can't not add to cart

WordPress does not have Add to Cart – what plugin are you using? You need to post on that plugin’s own forum.

I have Woocommerce plugin. It was works until yesterday night.

You can ask them here:

https://www.ads-software.com/support/plugin/woocommerce

You might want to deactivate ALL plugins and switch to a default theme to start troubleshooting this. First try with only WC active – see if it work okay. The add your theme and other plugins one by one to find what’s causing that.

Yes, I did what you said. But no luck.

You’ll have to ask WooCommerce or WooThemes.

Anyone can help?

It still can’t works.

Please help.

WooCommerce is a very sophisticated plugin and has a daunting amount of settings that we’d have to go through with you to even begin to guess the problem. You need to ask on their support forums. Make sure to explicitly say what changed since yesterday night.

I have post on their support forums. But no one reply. ??

Then you may have to pay for premium support unfortunately. Those guys are pretty good, they’ll get you fixed up.

How to pay for the premium support?

Register here: https://www.woothemes.com/my-account/ and then contact support from the dropdown in the top menu I would imagine.