Windows registry

There are only two options.

1. Use the Microsoft.Win32.Registry class to iterate through all the keys and subkeys until you find the value you are looking for.

2. Microsoft has a great (but not well known) tool for this - called LogParser.

It uses a SQL engine to query all kind of text based data like the Registry, the Filesystem, the eventlog, AD etc... To be usable from C#, you need to build an Interop Assembly from the Logparser.dll COM server using following (adjust LogParser.dll path) command.

tlbimp "C:\Program Files\Log Parser 2.2\LogParser.dll" /out:Interop.MSUtil.dll
Following is a small sample, that illustrates how to query for the Value 'VisualStudio' in the \HKLM\SOFTWARE\Microsoft tree.

using System;
using System.Runtime.InteropServices;
using LogQuery = Interop.MSUtil.LogQueryClass;
using RegistryInputFormat = Interop.MSUtil.COMRegistryInputContextClass;
using RegRecordSet = Interop.MSUtil.ILogRecordset;

class Program
{
  public static void Main()
  {
    RegRecordSet rs = null;
    try
    {
      LogQuery qry = new LogQuery();
      RegistryInputFormat registryFormat = new RegistryInputFormat();
      string query = @"SELECT Path from \HKLM\SOFTWARE\Microsoft where Value='VisualStudio'";
      rs = qry.Execute(query, registryFormat);
      for(; !rs.atEnd(); rs.moveNext())
        Console.WriteLine(rs.getRecord().toNativeString(","));
    }
    finally
    {
      rs.close();
    }
  }
}

NB// This answer is quoted from stackoverflow.com[^] but copied here for the benefit of the code snippet.