COmp startup issue

when i try restarting then it just shows the intel motherboard page and then the screen goes blank with just a cursor blinking on the top left hand side

but now i changed my booting option to 'BOOT FROM CD' and as my ROM drive is empty it does not detect any CD and boots properly....

when i again changed the booting option to the normal thing then it does not boot again.

Now i want to know, How i can restore the earlier boot setting without the screen going completely blank with just a blinking cursor.