OK. If you haven't already, please reset the BIOS settings to default settings.
To do that, press the F9 key while you are in the BIOS. Confirm by pressing Y when asked.
After that, press the F10 key. Confirm by pressing Y when asked.
The laptop will then restart. Check if there are any changes.
OK, see you later.
Since the Acer Aspire R7 doesn't have an optical drive, you can either get an external one, or use a bootable USB drive to load Windows 8 repair or installation media.
I see you mentioned creating a bootable Windows 8 USB thumb drive. Have you tested it on another computer to see if it is really working?
I suggest testing the USB thumb drive on another computer. Change the boot sequence there and see if that computer will boot from the USB thumb drive.
Sure, no problem.
So you couldn't test the USB thumb drive?
Trying to boot from the USB thumb drive cannot crash Windows Vista. Something else happened that caused that problem.
Do you have another computer where you can test booting from that USB thumb drive?
It is possible that you had already set booting from USB in the Boot tab, but the USB thumb drive is not bootable.
I am following up with you to check if you were able to boot from the CD/DVD drive.