Laptop chargers have two wires that connect to the charger itself (the "brick"). One wire connects from the charger to the computer and the other connects from the wall outlet ("mains power") to the charger.
On many chargers, including the one for the HP G72, the wire that plugs into the wall outlet can be disconnected from the charger, but the wire that connects from the charger to the computer is permanently connected to the charger. The reason that the wire to the wall outlet disconnects is so that the same charger unit can be sold with a wire and plug that is appropriate for different wall outlets in different countries.
I think you left some words out of your sentence.
- Does one of the wires not stay connected? If so, which one?
- Or do the "solid white light" and the "orange charging light" not stay lit when everything is connected?
- Does "replaced cord" mean that you bought a complete new charger (which comes with the two wires described above) or you only purchased the wire that goes between the wall outlet and the charger?
Regardless of what you bought, it sounds as if you need a new charger. Plug a lamp into a wall outlet to confirm that the wall outlet has power. Then remove the laptop's battery and connect the charger to both the wall outlet and the laptop. If the laptop does not turn on, you need a new charger.
If it's the latter, and the battery does not charge nor does the laptop get power even when all the wires are plugged in to their respective connections, then you need a new charger.
It's possible, but far less likely, that the charger is OK but the circuitry inside the computer is damaged. The only way to determine if the charger is OK (aside from the test described above) is to measure the output voltage with a test meter.
When buying a replacement charger, you need to look for 3 things (see the pictures here http://tinyurl.com/y7a6ptrj):
1. The connector tip (the part that physically connects to the computer). This must be the same size and shape as the original charger's connector. Most after market chargers that claim compatibility with your specific model will almost certainly at least have the correct connector tip.
2. The charger's output voltage. This is shown on the label on the charger. The standard charger for your laptop has an output voltage of 18.5 volts
3. The charger's output current. This is shown on the label on the charger. The standard charger for your laptop has an output current of 3.5 amperes.
The charge should also indicate "watts" which is its power rating. The standard charger is 65 watts.
A "heavy duty" charger is also permissible for your computer. This is 90 watts with an output voltage of 19 volts and an output current of 4.74 amperes.