I Need the existing custom mat builder app on our site fixed.

General information for the website: Yoga Mat Customization Site
Kind of development: Customization of existing website
Description of every page/module: The app needs to work again, by allowing users to upload there images to our server and for us to be able to see the images in the order in the admin panel.
Description of requirements/features: Hi,
We have a website app which is written in php, the app basically allows the user to choose an image from there computer and make there own yoga mat design.

The app was created by a developer who we are no longer in touch with, the app has recently gone down. I believe this is because the hosting for where it was held has gone down.

We need to get the app working again, it apparently is as easy as swapping the URLS over to another server so the images can be stored there instead.
I believe the code below is also needed in the process somewhere.

At the moment when a customer tries to use the app it just says saving and does nothing, we were given the code below by the original developer who said if we pass this on to another developer they will no what to do with it.

The problem happens when trying to save after you have built your mat.

Also in the back end of the website when we get an order, there is a url link which we can open in the browser which shows us the mock up.
CMS and Admin requirements: Shopify Platform
Extra services needed: Installation
Specific technologies required: PHP
Extra notes: