Today, i messed up with my laptop. It all started by learning to create a Debian bootable USB stick as given in http://blogs.koolwal.net/2009/02/25/installing-linux-on-usb-part-7-install-debian-linux-from-usb-drive/ and at the step of extracting the boot.img.gz file, i gave /dev/sda which is my laptop hard drive instead of USB drive. After this accident, i could not reboot my system. I cannot go beyond the boot screen showing the compaq logo and i cannot access BIOS also. I had a talk with HP service center and they have asked me to visit them tomorrow. When i googled for the symptoms, i got many solutions like flashing BIOS etc.. but i don’t want to take risk.