Option Explicit
Private Sub CommandButton1_Click()
Dim Rng As Range, T(), L As Long, C As Long
Set Rng = Worksheets("MEMBERS").UsedRange
On Error Resume Next
L = WorksheetFunction.Match(txt_user, Rng.Columns("A"), 0)
On Error GoTo 0
T = Rng.Value
If L > 1 And Txt_passe.Text = CStr(T(L, 2)) Then
For C = 6 To UBound(T, 2)
Worksheets(T(1, C)).Visible = IIf(IsEmpty(T(L, C)), xlSheetVeryHidden, xlSheetVisible)
Next C
Sheets("SOMMAIRE").Activate
ActiveSheet.Cells(3, "F").Value = "Bonjour " & T(L, 5) & " " & T(L, 4) & " "
' etc.
Else
MsgBox "L'utilisateur ou le mot de passe est incorrect", vbExclamation, "INFORMATION GESTRIALS"
End If
End Sub