Not detecting SATA NAtive hard drive

We have four cases here.

The BIOS is set incorrectly: e.g. it may specify "Boot from either CD, USB or network BOOTP", but you have none, so it won't boot. You need to enter the BIOS and set the boot device to "Hard disk". This is of course the easiest and most easily solved case.

The hard disk is intact, but the driver is not installed or has become corrupt: you need to temporarily set the BIOS disk setting from ATA to AHCI and vice versa, booting into safe mode if possible, installing the drivers while the BIOS allows reading the disk and setting it back afterwards. This is a common occurrence with some systems (notably my Dell XPS 1330).

The hard disk is intact but the partition is damaged or not bootable. The data are still there, but the system doesn't know how to read them. You will need a disk recovery tool to correctly set the boot flag. UBCD may help you if you're familiar with this kind of troubles, otherwise you'll need a GUI tool such as Paragon's.

The hard disk is damaged or otherwise malfunctioning (loose cable, bad motherboard chip). Here you'll have to send the computer to assistance, or maybe you can try extracting the HD from the notebook and installing it into an external SATA to USB enclosure, to be connected to another PC and checked for data integrity. This will still leave you with a unstable PC, but at least you'll have your data available (and if it's just a loose cable, you'll be able to tighten it).