Edit an exesting file Excel with framework Laravel

I want to edit an existing file named 'myfile', I want just to export it before adding some data...and I have this problem :

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PHPExcel_Reader_Exception in Excel2007.php line 82:

Could not open C:\laravel\compta\files/Med for reading! File does not exist.

And this is my code in controller :

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public function export(){

Excel::load('files/Med',function($excel) {

$excel->sheet('Sheetname', function($sheet) {

    // Sheet manipulation

});

})->export('xls');

}

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How can I please export the file 'Med' ?

via Chebli Mohamed