Compaq screen goes blank after power up?

When yo upower up press F! or F2 or "del" key to enter in bios then check your harddisk is detected? if your harddisk is sata then enable sata option in bios then save settings.
If every thing is fine then it should be dispaly resolution issue.
When yo upower up vthe computer press F8 key then enter in enable vga mode then go to control panel then dispaly proeprty-> settings ->change screen resolution to 1024*768 then restart .

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