Hi, I am Dave, I will help you with this.
1
Can you not access the recovery environment using these steps to try the various recovery options?
Start your PC, just as Windows attempts to load (spinning dots), press and hold Power Button for 5 - 10 seconds to perform a Hard Shut Down
Do this twice
On the third start Windows will boot into the Recovery Environment and from there you can access System Repair, Safe Mode, Command Prompt... etc.
2
You indicate you cannot boot from your bootable USB,, what problem are you having with that, what error do you see?