What BIOS version did you have before you changed to 3.20? On the ASRock page for your board (the USA site, if that makes a difference) the only BIOS versions shown are 3.10 and 3.20. 3.10 has a required driver, really the Intel Management Engine, and a new version of AXTU. Were you using 3.10 and loaded the Intel ME software that is necessary? If you were using a BIOS version earlier than 3.10, I assume you would need that version of IME with 3.20.
One potential option (?) for you might be, there is a Beta BIOS version L2.11H, in the "Beta Zone" download area. Yes not the best option, and will the BIOS update program allow you to load it over 3.20? I don't know.
A guaranteed fix would be to buy a new BIOS chip, with an earlier BIOS version on it. That might not be easy to do where you live, hopefully it is. I've read about others doing that with other boards, getting the chip and BIOS from ASRock or even eBay. You might need to install Windows 8 again, but at least your PC would work.
You might be a victim of what I call the "BIOS updates for Ivy Bridge CPUs but using Sandy Bridge CPU syndrome". That is, the BIOS updates for IB CPUs cause issues with SB CPUs. I've seen that with other mother board manufactures products, and apparently on some ASRock boards too. I won't put the latest BIOS on my ASUS P67 board, since I use an i7-2600K in it, and users have reported strange issues when using that BIOS (for IB support) on their PCs with SB CPUs. This may not matter in your case at all, just FYI if you've never heard of it.