Since this tower has stabilized again after deleting the old OS and removing the slotted graphics card causing all the upsets, my GRUB menu has dissappeared? How would I get it back?
So, you have only Zorin OS installed? If yes, it wouldn't be directly needed except for something like changing the Kernel.
But what You could do is: start Zorin OS on a USB Stick and choose the Try Mode to run it on the USB Stick. Choose there the Program ''Boot Repair'' and let it run and then look if the GRUB Menu is back.
Another Thing: Open the Terminal and type there sudo nano /etc/default/grub and in the opening Window look in the white Textblock for the Line GRUB_TIMEOUT and if it is set to 0. If it is, change the Number. That are the Seconds how long the grub Menu appears. When You set it for Example to 20 it will appear 20 Seconds. If You set it to -1 it will stay until You choose something.
It re-appeared this morning and I started in repair mode. I have seen the boot repair option in there. I did have trouble with USB zorin install boot in that no screen appeared after selecting "Try Installing Zorin", but since I seem to have start normal now, I will try again, and can also use the sudo commands. Thankyou.
No joy with boot repair under the usb zorin install use. I did the sudo nano and changed the value of the grub timeout to -1 (supposed to stay and not timeout?). However, I tried several ways to save/execute that and have no results for it?
I have a long winded way perhaps by also installing completely another zorin version (16.3) and then maybe the boot grub will re-appear. Then I can use the repair mode to fix my current version and then when done deleted the zorin 16.3 partition?
Yes, when You set it to -1 the Grub Menu stays until You make a Choice. I had to explain it a bit more, sorry. Do it so:
Open the Terminal and type sudo nano /etc/default/grub and type in Your Password. In the opening Window look in the white Textblock for the Line GRUB_TIMEOUT= and look what Number there stands:
If there stands a 0 Grub is turned off. When You take a number higher that 0, the Grub Menu will appear that Value in Seconds. When You take 10 it will be 10 Seconds. With 20 it will be 20 Seconds and so on. With -1 it is like already explained. So, choose what You want and type it behind the = and then You have to save that.
To do this press ctrl+o to save the Change, Enter to confirm and ctrl+x to close the Window. Back in the normal Terminal Window type sudo update-grub to update the new Grub Settings. It is important that to do that! Without that the Changes will not affect the Grub Menu.
OK, I did save the -1 setting. A bit strange, bit the last command gave this looping - ruce@LINUX1:~$ sudo update-grub
Sourcing file `/etc/default/grub'
I will re-start and see what happens.
Very grateful for your help.