I have a windows 8 laptop. I was using it and it suddenly went out. When i try to turn it on the power light turns on but nothing else happens. The computer has important files and i do not want to replace it.
Assuming that the system is damaged in some way and it's not a power supply/battery issue, and that no encryption was being done:
You will need a working windows machine and an external USB drive dock.
Remove the HDD from the laptop and put in the dock, do not turn the dock on yet.
Boot into windows from the other machine.
Make sure all autoplay functions turned off.
Once fully booted, THEN turn the dock on.
Browse to the appropriate folder(s) and backup your important files to the other machine.
No assumptions can be made on the why the system isn't doing anything.
It could be a bad power supply adapter not allowing sufficient charge if the computer can run on the adapter.
It could be a broken power supply connector in the computer.
It could be a bad battery pack.
It could be a blown capacitor on the motherboard or other failed component.
It's a Windows 8 computer, guessing probably out of warranty.
If it's still in warranty, great! Backup your important files to another computer and send it in for repair.
Otherwise, how much money do you want to put into it to get it diagnosed, and possibly repaired in situ, vs replacing it?