Network Location in EC2 instance (Windows Server 2012) inaccessible: Network path not found. How to track/restore?

I suppose my main question is this: How can I find out which of our AWS resources is attached to a specific internal IP address?

Some background: I inherited responsibility for our AWS account from someone who left the organization. This account was probably established some time in 2009. We have several EC2 instances. Some are ColdFusion web servers, and one is a Windows Server 2012 console.

Earlier today, the web servers started returning 500 errors. I can't even access the ColdFusion Administrator, so I know this is not a problem with our code. (We also didn't change any code; it just suddenly stopped working this morning.) I believe these servers are configured to access a shared network resource, and the source code for our web sites is located there. I suspect that this resource where the code resides has become inaccessible somehow.

We can usually access that shared resource from our Windows Server 2012 console. It has a virtual drive mapped to this shared network resource where the code lives. I can see the IP address of the resource, but I'm not able to learn exactly what it is and where to find it in our AWS services. In Windows PowerShell, I tried using tracert on that IP address, and the request timed out. But it did return a private DNS name for that IP, which looks like "ip-000-00-00-00.[zone].compute.internal". I can't find this IP address in our EC2 or S3 resources, and I don't know where else to look.

If I could just find the resource associated with that internal IP, maybe I could restart/reboot the service and bring all our web sites back.