Hi Sekerolan,
Thank you for visiting the HP Support Forums and Welcome. I have read your thread on your HP Pavilion g series Notebook and getting a blank or black screen on startup. Try performing a hard reset. When performing a hard reset please note remove any and all USB devices, and remove memory cards from the card reader slot. Disconnect all non-essential devices. If that does not help try to follow this document.
Hope this is helpful.
Thanks.