TOSHIBA LAPTOP WILL NOT BOOT, PLZ HELP?

ok, heres the info, it is a 3 month old toshiba laptop, and when i start it up, it has the underscore in the top left corner (like normal), it shows the toshiba bios inside sign and it has the underscore again and then gos black even tho it is still on, I HAVE CHECKED THE INTERNET, they give me instructions that i cannot use because i can't use the computer (i.e download new bios), your help would be greatly appreciated