Recover Hard Disk that was used for Linux
 

I have 2 hard disks. 40 and 120 GB respectively

since I had critical data to be dealt with in Windows, I kept windows and linux away from each other. I installed 4 flavors of Linux on the 40 GB drive just to try it out. When using Linux I disconnected the 120 GB Windows hard drive from the IDE cable

Now because of a space requirement I deleted all Linux partitions. The problem is that the 40 GB is not being recognized by Windows.

I tried fixing MBR, checking the master-slave setup, my IDE cabled etc. Please help me recover this HDD as I need it urgently.

you'll want to use a live CD such as Knoppix to do a low-level format on the hard-drive. winxp should then recognize it, then you can format it as NTFS

I assume what you mean by "Not recognized by Windows" is that you don' t see the drive in My Computer.
Try this.
(Assuming XP)

Go to Start>All Programs>Accesories>Administrative Tools>Computer Management
(on Win2K - right click My Computer, and Choose "Manage")

When this comes up, underneath "Storage" - choose "Disk Management"

Find your blank drive, and right click on it, and choose "New..."

I forget the symantics of this here, but essentially, you need to create a new logical partition.

Once this is done, you will see it in explorer.

use a linux live cd such as knoppix so that your 40G hd is recognise again (with any luck).
then use cfdisk /dev/hd? to delete previous partitions and create a VFAT partition.
Windows should recognise this when you log out then.
PS: replace ? with letter a,b,c, or d, under which your 40G is recognised.