Keyboard and mouse wont work in BIOS using advanced startup option

I wanted to switch OS to windows 7 from windows 10 so I used the USB method. When I booted up my USB I got into windows installation for windows 7, however, I couldn't use my mouse or keyboard. I edited USB settings in the UEFI bios and I also heard somewhere that I should change my boot order. Due to changing my boot order my computer has the checking media presence >media present start pxE over IPv4 and then IPv6 after which my old OS (windows 10) loads perfectly fine. However I cant access the bios anymore through pressing del or f2. I can only access it when I use advanced startup options through windows. When I do this my mouse and keyboard won't work. It works perfectly fine otherwise. I've tried using a PS/2 adapter but it doesn't work at all. I've also tried resetting my bios through removing the battery but my motherboard doesn't allow me to do so. Please help I'm deperate