Booting in secure mode- UEFI

Hello everyone,
I tried to install Linux on my new laptop but stopped after encountering some issues during the installation process. I reformatted my hard disk to perform a clean install of Windows 8. When installing Linux, I disabled the secure boot and boot from CSM instead. Even when I installed Windows 8, I used the same booting option. My problem now is my product key. In order to get it, I will need to boot to secure mode. But when doing this, I cannot find any booting option. Maybe this is because I tried to boot from CSM. However, I cannot install from USB either in secure mode. There is no options available. Can anyone help me through this?
