private string ResetAndBackupUserConfig(string userFile) { if (string.IsNullOrWhiteSpace(userFile)) { throw new ArgumentNullException(nameof(userFile)); } string userFolder = Path.GetDirectoryName(userFile); string userFileName = Path.GetFileNameWithoutExtension(userFile); string userFileExt = Path.GetExtension(userFile); string backupFile = Path.Combine(userFolder, string.Format("{0}.{1:yyyy.MM.dd.HH.mm.ss}{2}", userFileName, DateTime.UtcNow, userFileExt)); File.Move(userFile, backupFile); AppVM.ResetUserConfig(); AppVM.SaveUserConfig(); return(backupFile); }