Anyone got idea why sata m2 is not recognised on this old laptop? It was not recognised even during installation process. Storage drive itself is working (checked with another computer). Already checked options in Bios. Curently machine running Linux. 
Discussion
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Is the BIOS upgraded? Is the M.2 drive possibly too modern and not backwards compatible with whatever that old laptop supports? Also possible the firmware of the drive has issues with the laptop.
Basic question but did you try formatting it on another machine first?
Since it doesn't even get recognised during the install process that sounds like a hardware or firmware issue to me but worth giving the formatting a go.
Newer bios versions for this laptop is not available anymore. I'll give it go with formating again and will try another brand m2, if that not helps. Thanks for your tips.🙏🏼
No problem, thank you for the zap! There's different versions of M.2 drives, not all are made equal. If you're using one that's just one generation more advanced than your current one, usually it's backwards compatible, but if the laptop is more significantly outdated it could simply be that the drive just isn't compatible with the mobo.
Probably a broken connection. Had this problem with the ribbon cable on a sata drive.
That could be a possibility, but I doubt that, because there was not plugged any m2 drives before on this laptop. I know for sure. I'll try with formating the storage drive externally for now.
First and most important question, does the BIOS show you the unit?
Bios looks "stripped", there no optional section for sata m2, except to boot all sata devices 
If you put a LiveCD (or usb) with some distribution (ubuntu for example) it could be that it mounts the unit. maybe it is a matter of the configuration of your OS.
The machine runs currently the Elementary OS, I did connect sata m2 externally to this laptop-it recognized, I even formated the sata m2 drive to ext4, but once connectd sata m2 back to laptop slot, sata m2 was not recognised.
Actually I found newer bios file , but it is in .exe format, does that mean I have to update thebios through windows?
Bios file was here: https://www1.medion.de/downloads/index.pl?op=detail&id=18617&type=treiber&lang=uk
is it sata m2 or nvme m2 ? older laptops use sata m2 https://www.kingston.com/en/blog/pc-performance/two-types-m2-vs-ssd
Sata , nvme m2 dont fit, I checked