Windows 7 - One HDD is missing after installing Windows 7

Guys I need help.

I had on my PC windows XP. Today I installed Windows 7. After instalation one physical HDD 500GB went missing.

I have 3 physical drives:

One HDD 250GB was split in 2 partitions: (C: E: Windows XP was installed on C: I reformated it with Windows 7 CD and installed on C: partition)
The partition that had E: letter before now is 000000 (D: )
Another physical HDD 500GB I can see (E: )

My externnal HDD 500GB i can see (G: before was I: )

But one my physical drive 500GB is missing.

So now I have:

Local Disk (C: )-Windows 7 on it
000000 (D: ) - physical Drive
Local Disk (E: ) - physical Drive
External drive (G: )

1 physical drive 500GB is missing.
I haven't dual boot or something like that before, so problem is not there.
I tried to run diskmgmt.msc but my missing drive is not listed there.

Guys I really need your help, would appreciate it a lot. Pls help.

Have you checked you BIOS to make sure it actually see's your 500GB HDD?

When I goi in into Bios Main Tab I have like:

SATA 1 My 250GB disk with windows
SATA 2
SATA 3
SATA 4 my DVD optical device
SATA 5
SATA 6

Checked that all the connections are in place?

Good morning Hesa, welcome to the Windows 7 Forum.
SYMPTOM: As you stated after having all your physical drives show under Windows XP, you now only show 3 drives?
As stated, the drives show in BIOS but not in Windows 7?
Opening up disk Manager you are also not seeing the drive?

Possible Solution: It is possible the following occured!
Under disk management see if the physical drive shows with out a letter.
If it does you must put a VOLUME on the drive, assign a letter and reboot.

Regards,
Adrian

I didn't touched my PC inside. Connections are llike they were before.

I tried disk management. My 500GB HDD is not listed with or without letter.

I'm thinking this is possibly a hardware fault. nothing else explains it, if the BIOS doesn't show it at all, then its defiantly hardware.

Is your external HD USB or eSATA?

Check Device Manager for yellow triangles with !, this will usually indicate a new driver is needed.

Have you tried Disk Management > Action > Rescan Disks?

Yes. I tried rescan disks but it doesn't show up. My external is USB. In device manager I don't have any yellow Exclamation marks.
i don't think so that its hardware failure. Disk was function perfectly.