Solution to desktop computer not booting?

Disconect any added card it has if any , remove the video card and with a pencil eraser clean the gold contacts of the video card as well as the memory sticks , switch the memory sticks position if all goes well as soon you initialise enter the Bios to sett all the values to default if still can get it to start, turn it off disconect the power cable , press the turn off switch to descarge the capasitors and then remove the battery on the board for about a minute, re insert the battery that will reset the Bios , plug it back and try again.