About half of my customers are unable to add to cart, not browser specific

[ZonePhotoJim]

So, about half or more of my customers go to my site, zonephoto.us -and they are not allowed to add items to cart. I am having to invoice a large amount of them and as such, losing a ton of automation before we were forced over to the new format. The old format was way more user friendly and automated transactions went off without a hitch. This is not browser specific, it has happened to customers in every known browser. Please help!

[AshleyK]

@ZonePhotoJim what happens when your customers try to add items to the cart? Have you noticed if this happens with the same items?

[ZonePhotoJim]

It happens with all items, and now virtually with every order attempt, from every browser, and both mobile and desktop. Furthermore, I researched others with this same issue and attempted to fix by having the buy now button go straight to checkout and it goes to checkout right away and states that there is noting in the cart. I am at a complete loss, as my online store has become all but completely useless at this point. Why is there not an option to go back to our previous store exactly as it was? I was a very happy camper, and so were my customers. I am spending about half my day dealing with my customers calling, messaging, or emailing me that the store doesn't work, and I have had to invoice them all. It is very frustrating. To be perfectly honest there is not one single thing I like about the switch to weebly. It has been a completely horrible experience for me. If something does not give soon, I may have to find a different option entirely for my store and card processing provider. My customers are having a bad experience, and it reflects back on my company. I am at 90% now for failed orders. 

[ZonePhotoJim]

Literally nothing happens. The cart says there is nothing there when they attempt to add the item. Every browser. My software is all up to date and I can't even order from my site. Phone, Laptop, or Desktop, even iPad. I get the same response myself. Nothing there.