I then ran chkdisk and it didn't run but it caused all my icons on the desktop to disappear.
Running chkdsk shouldn't cause icons to disappear.
There's the possibility that the drive developed bad sectors.
The failure after "downgrading" to Windows 10 may be coincidental.
To check for bad sectors, you need to run
and reboot for it to run.
It can't do a thorough scan while Windows is running.
Now I can't open any program at all. When I click on anything, settings, file explorer, device manager, Internet exporer etc etc, they all go to the task bar and I can't open them. The icons just stay on the task bar until I close them. When I right click or left click nothing happens. If I right click it shows me the options for that program but clicking on the options does nothing.
Make sure the mouse is working properly. A bad mouse button can cause clicks not to register properly. You may want to try a different mouse that you know is working properly.
There could also be a problem with a stuck keyboard key.
If none of this is the problem, there are instructions on how to go back to Windows 10 herehttp://www.howtogeek.com/220723/how-to-uninstall-windows-10-and-downgrade-to-windows-7-or-8.1/
If you're not able to boot properly, you may have to boot to a CD in order to run chkdsk. Do you have a Windows CD? If not, maybe you could create a Repair CD on your working computer. https://support.microsoft.com/en-us/help/17423/windows-7-create-system-repair-disc