It is impossible to answer that question without access to you computer.
From what you say the explanation is
You “really” installed on C : not D : - you lost the wallet.dat of C: when it crashed.
What you might try? try to recover the C : drive with photorec / testdisk
otherwise Your original wallet.dat of D: (what is the size? what is the date? have you viewed the file contents?) could be copied back to the D : install folder or if you installed to the same directory the coins would appear after a sync.
Do you know anyone who is good at computers?