C# - cannot build DLL from extracted source code I changed

Hi Experts, i was recently asked to make a change to some code in a c#we based application. I decompiled the DLL with the code I need to change using software ILSPY and .NET reflector with filegen add on. I tried both these decompilers. i then saved the source code. changed the code that needed to change. I then opened the source code project file in Visual Studio 2017 to build the DLL file again. But getting like a 107 errors mostly reading identifier expected in parts of the code such as "public static readonly HomeController.<>c <>9 = new HomeController.<>c();" It shows that the "<>" in the code is the issue. Also more errors in the code read "Type or namespace definition, or end of file expected". Could this be due to encrypted code or obscurity? I urgently need to get this resolved.