I have an application in .net that gets more and more memory.
I’ve got some analyzes from a team member about the most common and most heavy instances that my application allocates.

The problem is that I don’t know what to do next.
The source code is huge!!
and I need best practice how to capture the problematic functions/lines of code.
p.s – I’ve tried using visual studio’s “.net memory allocation (sampling)” feature but it always failed to create the report. (guess it could be another question).
Visual Studio Profilerperfectly suit your requirements, it able to show a hot path in the call stack. You’ve to learn how to work with profiler so if you can’t generate Visual Studio profiler report and was not able to investigate how to do it – it worth start reading documentation first because no matter which tools you are using in this case.Below are useful links regarding Visual Studio profiler:
EDIT: Hot Path By VS Profiler: