Hello all. My first post on these forums. Hope I don't break any rules in it
I'll try to be short and clear in describing my problem, but please bare with me here as it's not the simplest of issues (not to me anyway).
I got a (at the time new) MSi laptop several months back with just a regular Windows 8 Core x64 on it and a UEFI boot system (or whatever is the name for "BIOSs"). At some point I had problems with the settings - I couldn't open any of my computer's settings - and I researched long and hard to no avail. So I installed Windows 7 32-bit (the only disk I had). Now, I'm trying to upgrade to Windows 8.1 Pro. I noticed that after the installation of 8.1 Pro my system was still running in 32-bit, so I made a bootable USB stick with the retail version of Windows 8 Core with no key just to get the system back to x64. It worked just fine. I cannot, however, boot in UEFI mode. I believe the partition got wiped somewhere in the Windows 7 installation. Whenever I enter UEFI by pressing the DEL button (I cannot see the UEFI firmware settings tile under the Troubleshoot option) I see the boot mode is LEGACY and when I change it to UEFI, save and reset, it doesn't boot, giving me a "No media found" error. I don't care about my settings/files as long as I get UEFI back with Windows 8.1 Pro running.
I googled long enough to know I'm not going anywhere if I don't ask someone with expertise on this matter.
My next attempt would be to try and install 8.1 Pro from USB stick, wipe all the partitions and hope the installer will create new ones. The reason this would work when it didn't before is because I had the OS running in x86 not x64 (which UEFI doesn't support). So maybe now that the system is back to x64 the Windows installation will restore the UEFI back to its original state.
Thanks in advance for any solutions