This topic doesn't belong to UBCD troubleshooting, but anyway...
If you *really* need the data in the HDD "immediately" (and you can't wait), then you need to take that HDD and connect it as a second HDD to another computer so to be sure that it is still readable. Don't boot with it in any other computer. Boot UBCD + PartedMagic to backup whatever you need.
That would be using a different computer, and if you can't wait.
Now, whatever happened to your current system, it seems that is not that much related to the specific HDD nor your optical drive, since no drive would boot.
So, unplug all your drives (HDD, optical, USB...) from both the data cable and the power cable of each. Then take out the CMOS battery, or, if you know where the reset cap is, use that.
For the battery reset jumper, keep it several seconds. The best practice though, IMHO, is to get the CMOS battery out for a couple of minutes (if you know how to do it without breaking anything).
Insert the CMOS/BIOS battery again (or remove the cap of the reset jumper), connect the power cable to your computer, but wait a couple of minutes before booting.
Still with no drive connected, boot into the BIOS and reset all values to "safe default". Save and reboot again into the BIOS.
Then change the BIOS to "optimal defaults", save and reboot again. Are the values being really saved? If the answer is "no", then you have your first clue.
If the values are saved, change back to "safe defaults" and save them. Reboot to confirm they were saved.
Now power off again the system and connect your optical drive only (both power and data cables). Boot into the BIOS, and configure it accordingly. The first boot might not recognize the drive, depending on the BIOS values (typically, LEGACY IDE, SATA, AHCI, RAID and USB values can prevent the BIOS from recognizing the drive). Save the correct values for your optical drive (SATA...) and reboot into the BIOS again. Does it recognize the optical drive?
Now insert UBCD and try booting with it (and no, your HDD is still not connected). Does it boot to UBCD?
Now power off again and repeat the procedure that you just did with the optical drive, but this time with the HDD. You can leave the optical drive connected too.
If the BIOS recognize both drives now, boot again UBCD. Success? Now try any "read-only" tool of UBCD / PartedMagic, so to check if the HDD is recognized.
If all the previous steps were successful, then try booting with your HDD as first booting device.