magento : fix checkout process on mobile app

we have an android and iphone mobile app thats integrated to magento. previous developer nanostuffs freelancer id "mankita" has ran away with the money i had trustingly released to them. their so called developers have just abondon not once but many times and took more than 1yr just to create this simple app. employers please take note of them. i have all the necessary source code and need to fix the following:- 1) ensure that checkout and mycart displays when item is added to cart and checkout. some strange issue is happening as old accounts are not working. but new registered account works 2) ensure that paypal and order process is working 3) orders must appear in the magento site and user must be able to see the order status payment terms is 100% milestone. full release only after all 4 issues are done and working properly. if you cannot accept this, please dont waste my time to bid. iphone and android app is native i have more upcoming projects but need developer.