gistfile1.txt

public string GetUserAvatar(int userId)
{
    var avatar = Directory.EnumerateFiles(Path.Combine(ftpServerPath, "UserAvatars"))
            .Where(x => Path.GetFileNameWithoutExtension(x) == userId.ToString());
    if (avatar.Count() != 0)
    {
        return String.Format("{0}{1}/{2}", downloadPath, "UserAvatars", Path.GetFileName(avatar.First()));
    }
    else
    {
        return string.Empty;
    }
}