Re: Computer would not boot after Windows 8.1 update
I would suspect a basic hardware problem, rather than a Windows problem, since no port responds.
First thought, reset the BIOS (many motherboards have a BIOS reset button on it, others you have to take the CR2032 CMOS backup battery out (with the PC powered off) for AT LEAST 10 Minutes to reset the CMOS (BIOS).
If that doesn't help, break the PC down to only the keyboard and mouse in USB ports, nothing else and try it.
Franklin D-10 Pedal Steel Guitar (primary instrument). Dobro, Tele, Gretsch Chet Atkins, 4 and 5 string basses, etc.
ASRock Z77 Professional Fatal1ty M/B, i7 3770 CPU, 16GB Ram, AMD Radeon HD 7770 Video, SSD and conventional hard drives, Win 10 (primary OS) and Win 7
Sonar Platinum 64 bit. Roland Octa-Capture, Steinberg UR44, ART Pro MPA II, Tranzport, X-Touch, JBL LSR308 Monitors
Ozone 5 & Melodyne
Member of Nashville based R.O.P.E. Assn.