Fatal error: Class 'Mage_Core_Block_Abstract' not found

[bounbran]

Hello guys, 

I am having an issue after modifying the profiler.php file, to allow the profiler on magento (via a tutorial seen on the net), 

  if (!$this->_beforeToHtml()

            || !Mage::getStoreConfig('dev/debug/profiler')

            || !Mage::helper('core')->isDevAllowed()) {

            return '';

        }

so that it looks like:

/* if (!$this->_beforeToHtml()

            || !Mage::getStoreConfig('dev/debug/profiler')

            || !Mage::helper('core')->isDevAllowed()) {

            return '';

        } */

The backend and frontend is not showing anymore (blank), I uploaded the orignal profiler.php file, empty the cache, disable compilation.

I got a fatal error : Fatal error: Class 'Mage_Core_Block_Abstract' not found in /chroot/home/,,,,,,,,,,,,,,,,,,,/,,,,,,,,,,,,,,,,,,,,,,,,,/html/app/code/core/Mage/Core/Block/Template.php on line 36

I uploaded the abstract.php file and the error disappeared, now i have a blank backend and frontend.

Any solutions for this problem, thank you