For Each c In Range("a2:a23")
dossier = Dir("C:\Windows\" & c.Value, vbDirectory)
If dossier <> "" Then
c.Offset(0, 1) = "It's OK !"
Else
c.Offset(0, 1) = "None"
c.Offset(0, 1).Interior.Color = vbRed
End If
Next c
With Range("a2:a23")
Set cel = .Find(dossier, , xlValues, xlWhole)
For Each c In Range("a2:a23")
dossier = Dir("C:\Windows\" & c.Offset(0, 0).Value, vbDirectory)
With Range("a2:a23")
Set cel = .Find(dossier, , xlValues, xlWhole)