Does your system have a "Fn" key? If so, try Fn+PrtSc. I that works it means the Function key operation is now opposite of what it once was. If that works... you'll either have a "hotkey" switch (usually ESC + Fn - if so there's usually a "lock" icon on the ESC key), a vendor supplied keyboard utility, or a BIOS setting. Since you recently had to clear your BIOS I'd suspect that's where it is on your system. Look for a "Function keys" setting and toggle it.