Probably should have had the coding specified, and the lines that have problems, so here:

Code:
    Dim fa As Single
    Dim fb As Single
    Dim fc As Single
    Dim fd As Single
    Dim levelno As Single
    Dim clno As Single
    Dim colour As Single
    Dim skno As Single
    Dim skilllevel As Single
    Dim levelno2 As Single
    Dim unlocked As Single
    Dim nameleng As Single
    Dim username = TextBox1
    Dim savecode As Single
    Dim roundno As Single
    Dim clskno As Single


    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        If CheckBox1.Checked = True Then
            fa = "Done"
        End If
        If CheckBox2.Checked = True Then
            fb = "Done"
        End If
        If CheckBox3.Checked = True Then
            fc = "Done"
        End If
        If CheckBox4.Checked = True Then
            fd = "Done"
        End If
        If fa = "Done" Then
            levelno = 0
        End If
        If fb = "Done" Then
            levelno = levelno + 2
        End If
        If fc = "Done" Then
            levelno = levelno + 4
        End If
        If fd = "Done" Then
            levelno = levelno + 8
        End If
        If colour = "Yellow" Then
            clno = 0
        End If
        If colour = "Orange" Then
            clno = 1
        End If
        If colour = "White" Then
            clno = 2
        End If
        If colour = "Blue" Then
            clno = 3
        End If
        If colour = "Green" Then
            clno = 4
        End If
        If colour = "Turquoise" Then
            clno = 5
        End If
        If (skilllevel = "Normal") Then
            skno = 0
        End If
        If (skilllevel = "Pro") Then
            skno = 1
        End If
        If (skilllevel = "Easy") Then
            skno = 2
        End If
        levelno2 = Chr(levelno + unlocked * 15 + 33)
        If levelno2 = "0" Then
            levelno2 = "z"
        End If
        nameleng = Chr(Number(username.length) + 8 * Rnd(3) + 65)
        levelno = Chr(levelno + 65)
        roundno = Chr(unlocked + 7 * Rnd(3) + 65)
        clskno = Chr(Number(skno) * 6 + (Number(clno) + 65))
        savecode = (username + "." + levelno2 + levelno + roundno + clskno + nameleng)
        Label8.Visible = True
        TextBox2.Visible = True
        If TextBox1.TextLength < 9 Then
            TextBox2.Text = savecode
        End If
    End Sub

    Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
        If ComboBox1.Text = "Orange" Then
            colour = "Orange"
        End If
        If ComboBox1.Text = "Blue" Then
            colour = "Blue"
        End If
        If ComboBox1.Text = "White" Then
            colour = "White"
        End If
        If ComboBox1.Text = "Green" Then
            colour = "Green"
        End If
        If ComboBox1.Text = "Turquoise" Then
            colour = "Turquoise"
            If ComboBox1.Text = "Yellow" Then
                colour = "Yellow"
            End If
        End If
    End Sub

    Private Sub ComboBox2_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox2.SelectedIndexChanged
        If ComboBox2.Text = "Easy" Then
            skilllevel = "Easy"
        End If
        If ComboBox2.Text = "Normal" Then
            skilllevel = "Normal"
        End If
        If ComboBox2.Text = "Pro" Then
            skilllevel = "Pro"
        End If
    End Sub
The bolded parts are the parts it says have problems