whats wrong how to repair

Start with some basics

It looks like you plug your monitor directly to the back of the computer motherboard, and use the integrated Nvidia 9200 graphics chipset to run your graphics.

Motherboard chipsets can fail.

Open your case, see if the cpu fan is turning, and if there is a small fan on the motherboard for cooling the chipset, make sure that fan is turning. If your graphics chipset can't cool itself it may be refusing to boot.

So you've checked your fans.

Next, you need to try a different graphics card. According to some reviews you DO have a PCIE x16 slot to plug a graphics card into your computer, but you probably don't have any additional power connectors. That means you'll need something like at Nvidia 1050 graphics card that is designed to draw it's power directly from the graphics slot.

With a different graphics card you will be able to troubleshoot further... but here is the deal.

You have a seven year old bargain basement computer.

It wasn't made to last, it was made to a price point... and it has given you years of good service.

Putting a lot of time and effort into getting this computer running is probably not a good use of your time.

Strongly consider getting a more modern computer. You can always get an external hard drive Sata to USB case and put the hard drive from your old computer in it to get at your files.

Of course, you might be able to install a better graphics card and everything will be fine... but my experience with Athlon II processors and Nvidia chipsets is that when they fail, they fail, and it's pretty much time for a new computer.

Sorry if I sound all gloom and doom. I do hope your computer starts working.