No bootable device | Zorin OS 16 lite

Hello
I am searching for help from few days and couldnt get my answer to this.
I have installed Zorin OS 16 Lite on my Acer device over Windows 7. (Clean installed it)
I have been using it for more then 5 Months and everything was working perfectly.
But now when i start my device, the following screen shows up and doesnt let me boot the installed OS:

I have found the same issue with other Acer laptops on this forum, but my settings page looks different:

Here is the modle of my device:

Hope You guys would help.

Do a non-destructive drive test... the symptoms point to your boot sector having gone bad (or having been overwritten by something).

If you boot the Zorin OS Boot USB, the Disks application has two SMART tests (short and long). Run them and let us know the results.

If the hard drive isn't SMART-enabled, you can also run:
sudo e2fsck -nccfkttv /dev/sda (or whichever drive you want to test)

You can view the options for that via:
man e2fsck

Were you always trying your Zorin or you installed it? Because reading No bootable device -- insert boot disk and press any key makes me think that you simply tried your Zorin while your boot disk was inserted. I don't remember my Zorin installation perfectly but when I plugged my USB stick with Zorin .iso I could start the installation normally from its installation interface, selecting Zorin on Boot section. Can't you retry installing Zorin as explained on Zorin official installation guide?