Hello, i bought a new asus motherboard and installed it. but when i turn my computer on it passes by this bios menu then into this black screen that says " Error loading operating system"
Just to make sure I get what you are saying, you have simply swapped your old motherboard in your system for the newly bought one?
Unless they use the exact same chipset, you really should do a new install of your OS.
But to your problem at hand, enter BIOS and make sure that your HDD is in the boot sequence.