Reflashing Bios

[Cheesewiz680]

Hi, i have a nasty virus that i believe is imbeded in my bios and i need to re flash them, I've already exhausted a lot of ideas and I'm left with this option or something a little more drastic. I've never had to do this before so i need a guide please. I have a MSI 945P/954PL Neo 5 if that helps