Q: How do I solve the error in the following code? private void Submit_Click(object sender, EventArgs e)
{
    if (textBox_Name.Text.Length == 0 && (textBox_Name.Text != "something" || textBox_Name.Text != "something"))
    {
        string message = "Your name is not " + textBox_Name.Text;
        string caption = "Error input";
        MessageBoxButtons buttons = MessageBoxButtons.RetryCancel;
        MessageBox.Show(message, caption, buttons);
        textBox_Name.Clear();
    else 
        MessageBox.Show("Good job something you know your name, LOL");
}

The message box always says that is Input Error as I added, only the message box with first if appears, when I type the correct name (something) also it's appearing the first part of the code :(
The else statement it is not even checked.
I am verifying the content of a textbox in the windows forms app.

A: your logic on the test appears strange with your balanced parenthesis.
if ((textBox_Name.Text.Length == 0) && ((textBox_Name.Text != "something") || (textBox_Name.Text != "something")))

in an abbreviated form to just show context
if(( textLength == 0 && ( text != "something" || text != "something" ) ))

Notice your text length is all by itself, THEN the AND of ( x OR x ).  The only time this will return TRUE is when you have AN EMPTY STRING in your textbox.  Because the string length will be zero length and the actual text will NOT be "something".
You probably need to do more testing such as...
if( string.IsNullOrWhiteSpace( textBox_Name.Text ))
{
   MessageBox.Show("You have not entered a value for the name");
   return;
}      

if( textBox_Name.Text.Equals( "something", StringComparison.CurrentCultureIgnoreCase )
{
   string message = "Your name is not " + textBox_Name.Text;
   string caption = "Error input";
   MessageBoxButtons buttons = MessageBoxButtons.RetryCancel;
   MessageBox.Show(message, caption, buttons);
   textBox_Name.Clear();
   return;
}

// else, must have had something valid other than empty or "something" regardless of case.
MessageBox.Show("Good job something you know your name, LOL");

