Hi a1ex2012,
Welcome to Sony Community!
The model VPCF12PGX is not compatible with Windows 10 operating system, thus, upgrading it to this version will show limitations and issues on your computer due to lack of drivers and software that helps the laptop to work properly.
To answer you question on how to access BIOS here is the link to guide you.
https://us.en.kb.sony.com/app/answers/detail/a_id/44078/c/65,66/kw/how%20to%20access%20bios
We recommend that you go back to your previous Windows version to prevent these issues. We only have Windows 7 drivers and software support for this model.
For further assistance regarding your concern, please contact the Sony offices/Sony representative offices nearest to your place of residence in Asia Pacific region http://www.sony-asia.com/countryselector.html?hpid=countryselector:AsiaPacific. Due to proximity, they are in a better position to respond to your questions or concerns.
Regards,
Jen
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