Write an iPhone application

I need someone with appropriate skills to help me find why one function in Visual Studio 2015 Web App is not working. Web App Software is for one hospital and it is managing patients, reviews and all related tasks. Each patient have SharePoint Site where all digital files are saved. Web App is using SQL Server as a database. If I'm right its written in ASP.NET. I manage to find function that based on name, surname and GUID communicate with SharePoint and returns SharePoint link to patient digital site or if there is none a link to a function to create digital site or an error that is currently our case. Our problem is that programmer recently died and left us with a full code. I know a lot about how this software works and how it is designed but my knowledge about programming and debugging in Visual Studio is low and I'm helpless. Software is on Croatian language, but I guess that this wont be a problem with me on another side... Also our friend that died was professional programmer and SQL expert and he left the code well organized. So I need someone who will ASAP remotely connected together with me inspect this code, debug it and fix links between Web App and SharePoint. Also there is a great possibility for hiring in future because we need someone who can replace our friend.