Voila enfaite tu avait re-ouvert la balise <?php dans un balise <?php deja ouverte donc beug .....
En espérant que sa marche ...
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta content="text/html; charset=ISO-8859-1" http-equiv="content-type" />
<title>co-voiturage</title>
</head>
<body>
<?php if (empty($_POST))
{
?>
<br />
<br />
<br />
<form method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>" name="inscription">
<div align="center">
<table width="314" border="0">
<tr>
<td width="162">Nom :</td>
<td width="11"> </td>
<td width="127"><input
name="Nom" /></td>
</tr>
<tr>
<td>Prénom :</td>
<td> </td>
<td><input
name="Prenom" /></td>
</tr>
<tr>
<td>Adresse :</td>
<td> </td>
<td><input
name="Adresse" /></td>
</tr>
<tr>
<td>Téléphone :</td>
<td> </td>
<td><input
name="Telephone" /></td>
</tr>
<tr>
<td>Destination : </td>
<td> </td>
<td><input
name="Destination" /></td>
</tr>
<tr>
<td>Heure de départ: </td>
<td> </td>
<td><input name="HeureDepart" /></td>
</tr>
<tr>
<td>Heure de retour : </td>
<td> </td>
<td><input name="HeureRetour" /></td>
</tr>
</table>
</div>
<br />
<br />
<div align="center">
<table width="200" border="0">
<tr>
<td><strong>Jour travaillé : </strong></td>
</tr>
<tr>
<td>Lundi</td>
<td> </td>
<td><input name="Lundi" type="checkbox" /></td>
</tr>
<tr>
<td>Mardi</td>
<td> </td>
<td><input name="Mardi" type="checkbox" /></td>
</tr>
<tr>
<td>Mercredi</td>
<td> </td>
<td><input name="Mercredi"
type="checkbox" /></td>
</tr>
<tr>
<td>Jeudi</td>
<td> </td>
<td><input name="Jeudi"
type="checkbox" /></td>
</tr>
<tr>
<td> Vendredi</td>
<td> </td>
<td>
<input name="Vendredi"
type="checkbox" /></td>
</tr>
<tr>
<td> Samedi </td>
<td> </td>
<td><input name="Samedi"
type="checkbox" /></td>
</tr>
<tr>
<td> Dimanche</td>
<td> </td>
<td>
<input name="Dimanche"
type="checkbox" /></td>
</tr>
</table>
</div>
<br />
<div align="center">
<input name="Validation" type="submit" />
<input name="Reset" type="reset" />
</div>
</form>
<?php }
if (!empty($_POST))
{
//Recup des variables.
$Nom = $_POST['Nom'];
$Prenom = $_POST['Prenom'];
$Adresse = $_POST['Adresse'];
$Telephone = $_POST['Telephone'];
$Destination = $_POST['Destination'];
$HeureDepart = $_POST['HeureDepart'];
$HeureRetour = $_POST['HeureRetour'];
$Lundi = $_POST['Lundi'];
$Mardi = $_POST['Mardi'];
$Mercredi = $_POST['Mercredi'];
$Jeudi = $_POST['Jeudi'];
$vendredi = $_POST['Vendredi'];
$Samedi = $_POST['Samedi'];
$Dimanche = $_POST['Dimanche'];
// Modif des varibles
if ($Lundi == 'on') $Lundi = 'oui';
else $Lundi = 'non';
if ($Mardi == 'on') $Mardi = 'oui';
else $Mardi = 'non';
if ($Mercredi == 'on') $Mercredi = 'oui';
else $Mercredi = 'non';
if ($Jeudi == 'on') $Jeudi = 'oui';
else $Jeudi = non;
if ($Vendredi == 'on') $Vendredi = 'oui';
else $Vendredi = 'non';
if ($Samedi == 'on') $Samedi = 'oui';
else $Samedi = 'non';
if ($Dimanche == 'on') $Dimanche = 'oui';
else $Dimanche = 'non';
// info pour la connexion
$host_db = "localhost";//host
$login_db = "***";//login
$pass_db = "***";//mot de passe
$db_db = "***";//nom de la base
//script de connexion plus complet que le tien (c'est celui que j'utilisai pour tous mes sites quand je fonctionnais sous mysql mintenant je suis postgresql qui est plus puissant mais plus compliqué)
$mysql_host="" . $host_db . "";
$mysql_login="" . $login_db . "";
$mysql_pass="" . $pass_db . "";
$mysql_dbnom="" . $db_db . "";
$db=mysql_connect($mysql_host,$mysql_login,$mysql_pass); //connexion a la base
mysql_select_db($mysql_dbnom,$db);// selection de base
// insertion sql
$sql = mysql_query("INSERT INTO co-voiturage ( `ID` , `Nom` , `Prenom` , `Adresse` , `Telephone` , `Destination` , `HeureDepart` , `HeureRetour` , `Lundi` , `Mardi` , `Mercredi` , `Jeudi` , `Vendredi` , `Samedi` , `Dimanche` ) VALUES ( '', '" . $Nom . "' , '" . $Prenom . "' , '" . $Adresse . "' , '" . $Telephone . "' , '" . $Destination . "' , '" . $HeureDepart . "' , '" . $HeureRetour . "' , '" . $Lundi . "' , '" . $Mardi . "' , '" . $Mercredi . "' , '" . $Jeudi . "' , '" . $Vendredi . "' , '" . $Samedi . "' , '" . $Dimanche . "')");
?>
<!-- On peut aussi faire un tableau recap -->
<table width="981" border="1" cellspacing="0" cellpadding="0">
<tr>
<td width="62"><div align="center">Prenom</div></td>
<td width="62"><div align="center">Nom</div></td>
<td width="71"><div align="center">Adresse</div></td>
<td width="73"><div align="center">Téléphone</div></td>
<td width="80"><div align="center">Destination</div></td>
<td width="86"><div align="center">Hr de depart</div></td>
<td width="89"><div align="center">Hr de retour</div></td>
<td width="59"><div align="center">Lundi</div></td>
<td width="63"><div align="center">Mardi</div></td>
<td width="77"><div align="center">Mercredi</div></td>
<td width="56"><div align="center">Jeudi</div></td>
<td width="72"><div align="center">Vendredi</div></td>
<td width="57"><div align="center">Samedi</div></td>
<td width="74"><div align="center">Dimanche</div></td>
</tr>
<tr>
<td><?php echo $Prenom;?></td>
<td><?php echo $Nom;?></td>
<td><?php echo $Adresse;?></td>
<td><?php echo $Telephone;?></td>
<td><?php echo $Destination;?></td>
<td><?php echo $HeureDepart;?></td>
<td><?php echo $HeureRetour;?></td>
<td><?php echo $Lundi;?>;</td>
<td><?php echo $Mardi;?></td>
<td><?php echo $Mercredi;?></td>
<td><?php echo $Jeudi;?></td>
<td><?php echo $Vendredi;?></td>
<td><?php echo $Samedi;?></td>
<td><?php echo $Dimanche;?></td>
</tr>
</table>
<?php }?>
</body>