Computer stopped recognizing my hard drive

[BRViking]

One fine afternoon, i tried to boot my pc and it didn´t start, saying i needed the windows setup disk... I tried to reinstall windows with the disk but then there was nothing on the hard drives list! there should be my WD Blue 500gb desktop HD... After a couple of tries my pc booted normally and i moved on with my life.
Yesterday i opened it for cleaning and to install my new memory stick. Tried to boot it and again nothing, even after lots of tries. It says that there are no primary disks nor secondary nor external disks on the startup screen. I am trying but i can´t even enter BIOS to checkout CMOS(might be just my stupidity)
For what i found here i guess it could be dead, is there anything i could do besides buying a new HD? please help

 

[Sooth1]

If you cannot enter your bios menu, there is some issue with the new memory stick you installed. Take it out and see if it works.

 

[Paperdoc]

For the hard drive, it MAY be just a loose connection. Some earlier SATA data cables would shake loose over time. With power disconnected, open the case and carefully disconnect both the wide power supply cable and the narrower data cable to the SATA HDD, then reconnect. Do this a few times to be sure the contacts are clean. Now, do the same for the narrower data cable where it plugs into the mobo port. Close up and attach power.

To enter BIOS Setup, most systems use the "Del" key, but some use others. So, when you first turn on, hold that "Del" key down - don't just tap it - until the BIOS Setup first screen appears. While you do that, watch your screen. It usually has a message about exactly which key to press to enter Setup. So, if yours does not use "Del", you'll see the correct key there.

 

[BRViking]

I have tried to re-connect the SATA cable lots of times in different SATA plugs and i got nothing, untill i took out the new memory stick and it worked!! Why would the new stick stop my pc from booting? can i make it boot normally with it on?