Ubuntu will not load from any source on my various platforms

I have downloaded and burned ISO images to disk and USB, I have also downloaded ubuntu direct to 3 computers Windows 10, XP Pro SP3 and windows 7 laptop.
No installed app on any of the computers is able to run the operating system, nor can I find anything online to do so.
Where on the various ISO downloaads and removeable media is the setup app that I can click on to run Ubuntu?
I,m about ready to give up on Linux!

Hello Sweeney - and welcome to the Forum.

Not sure what you mean by “I have also downloaded ubuntu direct to 3 computers Windows 10, XP Pro SP3 and windows 7 laptop.”.
The ISO image is just a single file that contains in a compact form all the files necessary to create an operating system. The ISO file is NOT an operating system.
Similarly Windows will not run any other operating system (except in a virtual environment) - Linux is not an application.

In order to run Linux you need to create a “Live Disc/USB”, from which you can either run Linux (but as a demo, as it’s slow method) or install it on your computer. In the latter case you can install Linux either alongside Windows or in place of it (recommended!).

You need a bit of software to “expand” the ISO into a working, Live disc/USB. I recommend downloading a USB stick writer such as balenaEtcher - Flash OS images to SD cards & USB drives. It comes with a USB stick formatter, which is useful. There is also https://unetbootin.github.io/ which allows one to create a live USB directly from a choice of Linux versions.

So don’t give up on Linux - you will be converted when you’ve given it a good try. Like the rest of us here. If you want to continue, download/install the USB writer and come back here.

Keith