How do I display a file's Properties dialog from C#?

Solution is:

using System.Runtime.InteropServices;

[DllImport("shell32.dll", CharSet = CharSet.Auto)]
static extern bool ShellExecuteEx(ref SHELLEXECUTEINFO lpExecInfo);

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public struct SHELLEXECUTEINFO
{
    public int cbSize;
    public uint fMask;
    public IntPtr hwnd;
    [MarshalAs(UnmanagedType.LPTStr)]
    public string lpVerb;
    [MarshalAs(UnmanagedType.LPTStr)]
    public string lpFile;
    [MarshalAs(UnmanagedType.LPTStr)]
    public string lpParameters;
    [MarshalAs(UnmanagedType.LPTStr)]
    public string lpDirectory;
    public int nShow;
    public IntPtr hInstApp;
    public IntPtr lpIDList;
    [MarshalAs(UnmanagedType.LPTStr)]
    public string lpClass;
    public IntPtr hkeyClass;
    public uint dwHotKey;
    public IntPtr hIcon;
    public IntPtr hProcess;
}

private const int SW_SHOW = 5;
private const uint SEE_MASK_INVOKEIDLIST = 12;
public static bool ShowFileProperties(string Filename)
{
    SHELLEXECUTEINFO info = new SHELLEXECUTEINFO();
    info.cbSize = System.Runtime.InteropServices.Marshal.SizeOf(info);
    info.lpVerb = "properties";
    info.lpFile = Filename;
    info.nShow = SW_SHOW;
    info.fMask = SEE_MASK_INVOKEIDLIST;
    return ShellExecuteEx(ref info);        
}

// button click
private void button1_Click(object sender, EventArgs e)
{
    string path = @"C:\Users\test\Documents\test.text";
    ShowFileProperties(path);
}

Call Process.Start, passing a ProcessStartInfo containing the name of the file, and with the ProcessStartInfo.Verb set to properties. (For more info, see the description of the unmanaged SHELLEXECUTEINFO structure, which is what ProcessStartInfo wraps, and in particular the lpVerb member.)

Various file properties are available from the FileInfo class:

FileInfo info = new FileInfo(path);
Console.WriteLine(info.CreationTime);
Console.WriteLine(info.Attributes);
...

To simplify handling Shell32 stuff and such, you could also use Vanara like:

using Vanara.PInvoke;
using System.Runtime.InteropServices;
// ...
void ShowProperties(string filepath)
{
    var info = new Shell32.SHELLEXECUTEINFO();

    info.cbSize = Marshal.SizeOf(info);
    info.lpVerb = "properties";
    info.lpFile = filepath;
    info.nShellExecuteShow = ShowWindowCommand.SW_SHOW;
    info.fMask = Shell32.ShellExecuteMaskFlags.SEE_MASK_INVOKEDLIST;

    Shell32.ShellExecuteEx(ref i);
}

and call it like:

ShowProperties(@"C:\The\Path\To\The\File.txt");