My brother took out his "old" laptop earlier and said that it was unusable because his child said spill on the keyboard.
however, the laptop is in itself and if the keyboard and mouse would work, you could continue to use it.
The problem is, the USB ports only work until the Windows symbol appears. From there, there's no power supply, which also invalidates the idea of the usb keyboard.
Now to my question: how can I either make the keyboard work again or connect a USB keyboard + mouse and then use it?
Ne keyboard is actually easy to change, whether it is worth the cost, you have to see.
I would open it first and see what exactly is there, maybe a cleaning is enough, you would have to check.
Possibly a new setup of Windows could help, as far as the USB ports are concerned, it could be that only one driver is faulty or that Windows itself has been damaging, if it has been around for so long as it goes before, I would have a hardware defect exclude first.
if the notebook has Bluetooth, you could connect a keyboard & mouse via it, would still work.
Open carefully and see how far the misfortune of the child has spread. As far as the problem with the USB ports is concerned, a new installation could actually help (alternatively, you can try out a live distribution of Linux via USB or something). Keyboards are abundant on Ebay, changing is usually not rocket science.