vmroyale thank you for your reply. I checked, I use Qemu Manager and helped myself with the following video:
When i went to CD-ROM option in Drives tab, I chose QCOW2 file to open it. After opening it, I clicked on green button in the toolbar and this is what Console tab showed (the content):
"Booting from cd-rom
999mb medium detected
cdrom boot failure code : 0005
boot failed: could not read the boot disk
Booting from hard disk
boot failed: not a bootable disk
FATAL: no bootable device"
I use Windows 8 and I know nothing about vmware (never used it). I also never used linux/ubuntu. It doesn't seem I am able to type anything under ''fatal no bootable device''.
What could I do? I repeat again the file i am trying to open (from hard drive) is .QCOW2 extension. It would be ideal if I could just convert the file to some other extension which I could open on Windows 8. Installing Qemu Manager caused some weird icon (looks like device or something like BD-ROM, don't know whats that) to occur on ''My Computer'' window.