How to install OS on NAS WITHOUT deleting logical drive

This is pretty confusing as you mention many things in your post and leave out how everything is setup.

Are you using a RAID setup?
Are you booting windows from a RAID setup?
Are you using a RAID controller card?

Second, not being able to access the bios on your computer has nothing to do with your HDD. If you cannot access the bios I would check all of your power connections and reset the bios by either finding the reset jumper or taking the battery out.

If you cannot get your bios to come up you have much bigger problems than your HDD.

Please answer the questions above and provide your computer specs so that we can continue to help.

What happens when you try to access your BIOS? Have you tryed a different mouse?

I have an adapter 32 tb RAID and also one 500 gig hdd not part of the RAID. I have the OS installed on the 500 gigabyte hdd that isnt a part of the RAID. Also I realised that I cant access my BIOS to set boot order or check setting the f6, f2, esc keys isnt working

Opps... try a different keyboard.

I would second anon1's advice, try a different keyboard and make sure its not plugged into a USB 3 port as they need drivers from the OS to work, your BIOS will not be able to read anything connected to your USB 3 ports.

Another question for you ... when you start your computer and cannot get to your BIOS does windows still start correctly?

Also please post your system specs, it will help us alot (aka, processor, motherboard, ram, etc.)

Thank you guys I resolved the problem by shutting down the server, remove the power cables. I also remove the CMOS battery and Disabled the adaptec RAID controller and reassembled and it worked. I guess the BIOS info. needed to be wiped . Thanks for all your replies I appreciate