Did not you customize your site in a child theme?. I think due to update you have lost your changes. Please always try to customize your site in a child theme. It is a good way to customize. Your store page is broken. You have to edit some CSS style. Please read this doc- http://docs.wedevs.com/how-to-fix-the-broken-store-page-of-dokan/. It will help you to do this.
Did you see the doc?. I did not tell you to provide details. But if you can not fix this then i can help you. You have to provide your login details here- http://wedevs.com/provide-login-details/. I will have a look what is going wrong.