MARKETPRESS: STORE PAGES ARE NOT FOUND

Hello there,
Till yesterday , everything worked. I could place an order, add it to the cart then go to checkout.
This was yesterday ! I have not the impression to have done much since , added a product may be ...
Each time that I try to go to either Payment it can not find the page store/cart anymore .
If I go to the page with the page editor , i have access to it but I cannot display it ....
Same happens for all the store pages under the page "store" such as checkout , cart ...
Even if remove the marketpress short code in the page and leave the page ( the cart for ex. ) then wordpress still cannot find the page. I tried to deactivate the reactivate Marketpress plugin ... still same result.
Any idea why ?
I granted you the access.
Thanks for your time.
Thierry