CDbConnection failed to open the DB connection: could not find extension

My Hosting Server php was upgraded to 7.2 and i got the following issues, The Programmer who did this website is not reachable now , can anyone please help me sort this,

this is very urgent

below is the error i see

/customers/0/f/7/ucanlogin.com/httpd.www/framework/db/CDbConnection.php(382)

370                 throw new CDbException('CDbConnection.connectionString cannot be empty.');
371             try
372             {
373                 Yii::trace('Opening DB connection','system.db.CDbConnection');
374                 $this->_pdo=$this->createPdoInstance();
375                 $this->initConnection($this->_pdo);
376                 $this->_active=true;
377             }
378             catch(PDOException $e)
379             {
380                 if(YII_DEBUG)
381                 {
382                     throw new CDbException('CDbConnection failed to open the DB connection: '.
383                         $e->getMessage(),(int)$e->getCode(),$e->errorInfo);
384                 }
385                 else
386                 {
387                     Yii::log($e->getMessage(),CLogger::LEVEL_ERROR,'exception.CDbException');
388                     throw new CDbException('CDbConnection failed to open the DB connection.',(int)$e->getCode(),$e->errorInfo);
389                 }
390             }
391         }
392     }
393 
394     /**

Thank you

your app is not able to connect to your database

In the php.ini enable pdo_your_db_driver.