Fais tourner ce code...
Sub toto()
Application.ScreenUpdating = False
For Each ws In ThisWorkbook.Worksheets
For Each c In ws.UsedRange
If c.Row <> 1 And c.Column <> 1 Then
If c.Value <> "" And IsNumeric(c.Value) = False Then
x = c.Value
y = Replace(x, ".", ",")
Z = Replace(y, " ", "")
c.Value = CDbl(Z)
End If
End If
Next c
Next ws
Application.ScreenUpdating = True
End Sub