Where did my C and D partition go?

I tried System Restore, and yet the computer is still unable to recognise the disk in there... Will replugging the hard disk again help?
Or let me try EASEUS software first.

Unbelievably the software Greg suggested recognised both hard drives on my computer but my Windows wouldn't...
Sorry for uploading lots of files in a day...

OK first things first things first - check if the issue is with the hardware or windows

reboot the system and het whatever key is required to enter the BIOS - check in bios to see if you can see the missing drive here.

If drive is visible here - the issue is a windows one - If not then you will need to open your case and physically check the connections to the drive

Disconnect the drive cabe at each end in turn and reconnect.

Reboot and recheck in BIOS

If still not visible you may have a failed cable or port or drive

You can if possible try to connect the drive to another port -

Reboot and recheck in BIOS

if the drive is then visible in bios it is port failure - Look to replace motherboard as soon as is practical

If possible disconnect the working drive and use the cable to connect the missing drive

Reboot and recheck in BIOS

If the drive is now visible the original cable is at fault - replace cable

If after these checks the drive is missing it may be a missing specialist windows driver or as the system has been correct it could be the drive has failed.

Barman58 said:

OK first things first things first - check if the issue is with the hardware or windows

reboot the system and het whatever key is required to enter the BIOS - check in bios to see if you can see the missing drive here.

If drive is visible here - the issue is a windows one - If not then you will need to open your case and physically check the connections to the drive

Disconnect the drive cabe at each end in turn and reconnect.

Reboot and recheck in BIOS

If still not visible you may have a failed cable or port or drive

You can if possible try to connect the drive to another port -

Reboot and recheck in BIOS

if the drive is then visible in bios it is port failure - Look to replace motherboard as soon as is practical

If possible disconnect the working drive and use the cable to connect the missing drive

Reboot and recheck in BIOS

If the drive is now visible the original cable is at fault - replace cable

If after these checks the drive is missing it may be a missing specialist windows driver or as the system has been correct it could be the drive has failed.

I believe it's Windows' fault. Sorry for not replying in a long time... this computer was heavily infected with Spyware. I fixed most of the malwares in here, but there are some leftovers.
What can I do to install Windows 7 in this computer? It just couldn't see my C or D drive anywhere.

So can you see all the drives now, including where you want to install Win7?

Due to the infection, it is strongly suggested you completely wipe any infected drive as thoroughly as possible before installing Windows 7.

Move data which needs to be saved to another HD, then scan it with Avast home free edition (use boot scan offered during install) and in safe mode with Spybot S&D. Then unplug the data drive during install.

This will completely zero out the Win7 target HD, the cleanest it can get:

boot from your Win7 DVD.

On the second screen select "Repair My Computer" then Recovery Tools list.

Open a Command Line and type these exact commands following instructions given:

DISKPART
LIST DISK
SELECT DISK # (for targeted HD)
clean all
create partition primary (for OS drives, data drives may be logical)
select partition 1
assign letter=c: (or whichever letter you want to give subsequent cleaned drives)
active (only use this step on the drive where you will be installing Windows 7)
format
exit

If you are uncomfortable using DISKPART commands, there is a program like Easeus which makes a bootable CD to do this with a graphical interface: Free Download Partition Wizard

Now you can reboot into the Win7 DVD and install Win7 to the active formatted drive

Plug ethernet and select "connect to the internet during install" to get latest drivers/updates, then Custom install, Advanced drive tools, format one more time and install.