My dell Inspiron won't turn on at all. How do you reinstall it to it's original factory settings with the 0 key?

Solution
If the computer wont turn on at all, meaning no keyboard lights, no hard drive or fan spin up then no key combination works as there is no power going to your board.

First thing to check is if power supply works. You can take a multimeter and a paper clip or piece of copper, put the paper clip in the center of the barrel plug on your ac adapter and touch the red lead of the multimeter to the wire, and the black lead to the outside of the barrel plug (do not touch your fingers to anything but the plastic on the multimeter (wont get shocked but you will throw off the test). If you get significantly less then the voltage stated on the adapter then it is bad and you need to replace it.
If the computer wont turn on at all, meaning no keyboard lights, no hard drive or fan spin up then no key combination works as there is no power going to your board.

First thing to check is if power supply works. You can take a multimeter and a paper clip or piece of copper, put the paper clip in the center of the barrel plug on your ac adapter and touch the red lead of the multimeter to the wire, and the black lead to the outside of the barrel plug (do not touch your fingers to anything but the plastic on the multimeter (wont get shocked but you will throw off the test). If you get significantly less then the voltage stated on the adapter then it is bad and you need to replace it.
 
Solution