HTML FILE IS:

<html>

<body  bgcolor="yellow" text="red" >
<form method="get" action="cookie6.php">
<p>Which car you want to buy?<P>
<TABLE border=2>
<TR><TD><input type="checkbox" value ="15"  name="text[]"><TD>Ferrari<TD bgcolor="blue" width="15px"> 15million</td></TR>
<TR><TD><input type="checkbox" value ="35"  name="text[]"><TD>Mercedes<TD bgcolor="red"width="15px"> 35million</td></TR>
<TR><TD><input type="checkbox" value ="50"  name="text[]"><TD>Bugatti<TD bgcolor="yellow"width="15px">50million</td></TR>
</TABLE>

<input type="hidden" value="1" name="check" >
<p>
<input type="submit" value="refresh" >
</form>
</body>
</html>

PHP FILE IS :

<?php
// echo "you want to buy<P>";
// if(isset($_GET['check']))
// {$car=array();
// if(isset($_GET['text1']))
// {echo $_GET['text1']."	ferrari<br>";}
// else {}
// if(isset($_GET['text2']))
// {echo $_GET['text2']."	merc<br>";}
 // else {}
 // if(isset ($_GET['text3']))
// {echo $_GET['text3']."	bugatti<br>";}
 // else {}
// }
if(isset($_GET['check']))
{	
	$sel_cars="";
	$count=count($_GET['text']);
	for($i=0;$i<$count;$i++)
	{	
		$sel_cars=$sel_cars.$text[$i]." ";
	}
}


?>

This is a basic code for finding which cars user selected.My program works if the checkboxes in the HTML file have different names but not if they have the same name.
Please I have tried it for more than 2 hours .....
What is the solution if checkboxes have the same name?

This is related to register globals*, you were using $text[$i] , if you don't define variable $text, then you get an error:

<?php
if(isset($_GET['check']))
{	
	$sel_cars="";
	$count=count($_GET['text']);
	for($i=0;$i<$count;$i++)
	{
		echo $_GET['text'][$i]." ";
	}
}
?>

Or use:

$text = $_GET['text'];
echo $text[$i]." ";

Bye :)

* http://php.net/manual/en/language.variables.predefined.php