It's time to explore data recovery software.
Partitioning the first drive is well known to make other drives vanish. I can't know your expertise level so here's common titles used by many users of many skill levels.
Zero Assumption Recovery.
Yes, there may be a way to use disk management but you've been there so I'll not go back there.
PS. This is another fine example where partitions and even other drives do not make for backup. I'm sure you read somewhere that your data would be safe if you put it on a second drive or partition. That's a myth.
My operating system is XP Pro. I have two Hard Drives. Drive C (250GB)
and the second drive is D (300GB). Before I partition my Drive C, both
of this Hard Drives C and D was recognized. I then partition my drive
C to C, D, E, and F. Now after the partitioning, my second drive cannot
be recognized. What went wrong? Can you please help me? Thanks