Directory.Exists() / Directory.CreateDirectory()

using System.IO;

// Check whether a directory exists.
bool exists = Directory.Exists(string path);

// Create a directory (also creates any intermediate directories recursively).
Directory.CreateDirectory(string path);

// Delete an empty directory.
Directory.Delete(string path);

// Delete a directory recursively (including all its contents).
Directory.Delete(string path, bool recursive);

// Get a list of file paths in a directory.
string[] files = Directory.GetFiles(string path);
string[] files = Directory.GetFiles(string path, string searchPattern);

// Get a list of subdirectory paths in a directory.
string[] dirs = Directory.GetDirectories(string path);

// Move (or rename) a directory.
Directory.Move(string sourceDirName, string destDirName);

using System;
using System.IO;

string basePath = "work";
string subPath  = Path.Combine(basePath, "logs", "2024");

// Use Directory.Exists() to check whether the directory exists.
Console.WriteLine(Directory.Exists(basePath)); // False

// Use Directory.CreateDirectory() to create the directory.
// Intermediate paths (logs/2024) are also created in one call.
Directory.CreateDirectory(subPath);
Console.WriteLine(Directory.Exists(subPath)); // True

// Create some test files.
File.WriteAllText(Path.Combine(subPath, "app.log"),   "app log");
File.WriteAllText(Path.Combine(subPath, "error.log"), "error log");
File.WriteAllText(Path.Combine(subPath, "data.txt"),  "data file");

// Use Directory.GetFiles() to list all files.
Console.WriteLine("--- All files ---");
foreach (string file in Directory.GetFiles(subPath))
{
    Console.WriteLine(Path.GetFileName(file));
}

// Filter by pattern (*.log only).
Console.WriteLine("--- .log files only ---");
foreach (string file in Directory.GetFiles(subPath, "*.log"))
{
    Console.WriteLine(Path.GetFileName(file));
}

// Use Directory.GetDirectories() to list subdirectories.
Console.WriteLine("--- Subdirectories ---");
foreach (string dir in Directory.GetDirectories(basePath))
{
    Console.WriteLine(Path.GetFileName(dir));
}

// Use Directory.Delete() to recursively delete the directory and its contents.
Directory.Delete(basePath, recursive: true);
Console.WriteLine($"After deletion: {Directory.Exists(basePath)}"); // False

Directory.CreateDirectory() does not throw an exception if the directory already exists, so you can call it safely without checking with Exists() first. Directory.Delete(path, true) permanently deletes the directory and all its contents with no way to undo — verify the path carefully before calling it.

Use Path.Combine() / Path.GetFileName() to build path strings, as it handles path separator differences across operating systems. For reading and writing files, see File.ReadAllText() / WriteAllText().