i cant reformat my laptop im inserting os dvd's and the screen display an arrow and black background and it doesn't progress and i also cant enter into safe mode what do i need to do? please help me. :c

Change boot order in BIOS for DVD to be first and hdd second. Let installation process reformat your hdd. For problem like this one there is more appropriate forum at Answers (http://answers.microsoft.com/cs-cz) as you have landed in quite different forum on security. Alternatively you can wipe out disk with third party disk partition software that you start from CD or USB. Regards Milos