You've managed to delete your C partition.
C and D cannot exist on one partition.
It looks like you've managed to wipe the C partition and extend the D partition to cover the full size of the drive.
you wouldnt have been able to do this whilst the computer was booted up in to Windows.
Have you been playing about with partition resizing?
You will need to try some software to try and recovery your C partition.
Give this a try: https://www.easeus.com/partition-recovery/index.htm
You could take your PC in to a shop for repair but if it's 8 years old i wouldnt bother.
even if the motherboard was replaced, the PC would not boot because there is no Windows installation.
your boot manager is missing, as is your active partition.