Checkout doesnt show products+no payment possible

Hi,
Since yesterday, when a payment is made, the checkout is going direcly to the shipping adress, not ever showing the selected products...

also, the order can not be finalised. Normally we only use Ideal, so now we selected other payment methods also like paypal,bank transfer but it's not transferring to the payment methods.

First I contacted the creators of the payment plugin, they did several tests, but they can not find an error in their software.
The advised me to reinstall hikashop, but before I do, I would like to know your opinion. Maybe anyone knows what I can do to solve this?

thanks for reading!

solved: it was a problem in the checkout workflow...