One reason to have a bootable Linux DVD or USB Flash drive is to find out if a problem is software or hardware related.
If your computer boots up ok on Linux,
then you have the valuable info that it is software related.

Both Apple iOS and Android smart phones have Linux as their “guts” so nearly everyone has used Linux, just do not know they have.

I carry Knoppix Linux on a tiny 8 GB usb flash drive the thickness of a nickel in my wallet.
This can be done with Linux Mint, Ubuntu Linux, Red Hat Linux or whatever.

Puppy Linux is a special flavor for running on really old computers.

If you can troubleshoot an old car,
you can learn to run Linux on a computer.