Thanks for the suggestions.

Write-to-USB I was trying to download was just called mkusb. At least that was the apt-get name. I can't recall what I used when I switched to LL but that was made from windows on the laptop that's down. I do remember finding it quite difficult to do. I find this sort of OS thing difficult to do in general.  As I'll need a new USB anyway (all my others have other stuff on them) I think I'll try one of the ready made ones.

Linux Lite  (and many others) recommends creating the installer with etcher these days:
https://www.techsolveprac.com/install-linux-lite-usb-windows/

My main Linux Lite laptop has gone T--sup & I'm in need of a live USB to retrieve my home folder files & replace the OS (With ubuntu). Trying to follow an LL tutorial to create one has already run into problems just trying download an app to write to USB. (my backup laptop - the one I'm using now - is also LL.)
I struggle with this sort of thing when everything goes as it should.

I'm looking at the plethora of ready done live USB's on ebay for less than £10. I know Ubuntu/linux is a free OS but this would, at first sight, be a hassle free way to get what I need fairly quickly.

Has anyone else used one? or know of a better (ie trusted) source than ebay ?

I feared as much. For me I think the live USB will be the less stressful. I'm not overly familiar with the workings of LL & not worked in root before. Running ls does show my home folder stuff so I don't want to bugger that up if I can help it.
 As I want to change to something else anyway I'll make a new live USB ( have to make a fresh one anyway). Once I've done that I may need some help accessing my old files to back them up but deal with that at the time.

Latest update on what's not happening with HP laptop.

Mouse does not do anything in command line. There is no mouse cursor. Clicking buttons, scroll wheel & moving it about does zero on screen to show for it. It will not highlight any text (as there is no mouse cursor to target anything with.) Mouse works in command line on this laptop though (also running LL) when summond from desktop. Maybe that's because it's not getting to command screen through the desktop?

Trying to get the desktop from generic options only results in command line/screen as per trying to boot with straight LL. Recovery mode lists lots of stuff before giving a recovery screen inc. failed actions & errors. Such as:
 dev/sda1 contains a file system with errors. check forced.

 I can list more if that might be useful. Recovery screen options :
resume
clean
dpkg repair broken packages.
fsck
grub update grub boot loader
root drop to root shell prompt
system-summary

Choosing dpkg gives a warning about making certain files read-write (forgot take picture of that one) & I didn't proceed.
Choosing system-summary gives a very brief flash of 2 lines of text such I had to photograph them to read:
cat: sys/devices/system/cpu/cpu0/cpufreq/scaling _available_frequencies: no such file or directory
/lib/recovery-mode/system summary:29:/lib/recovery-mode/options/system-summary: arithmetic expression: expecting primary: " / 1000"

It seems to recognise the external HDD as it returns:
[ 152.519172] sd 2:0:0:0 No Caching mode found [ 152.519426] sd 2:0:0:0 [sdb] assuming drive cache : write through
in the command prompt after plugging it in. Does similar with a USB flash drive but numbers in brackets differ. However running , df | grep media , returns to a blank command prompt with both. df media, same thing.

Do you agree with Darry's suggestion that live USB OS would gain me access to my files for back up ? He suggested Puppy.

Thanks again both for the help you've given so far.