Dual Boot-Ubuntu along with Win 7, ubuntu not detecting the partitions on HDD on which Win 7 is currently exist as sole OS

I recently (19.03.2015) purchased Dell Insp 15 3543 (Ubuntu OS). As I wanted to Dual Boot Ubuntu along with Windows 7, I did not complete the Ubuntu installation (Pre-provided with Laptop, & started Installing windows 7 from Installation CD. While, at the option of selecting where to install the Win 7 OS, I deleted all partitions:
A. Partition 0 OEM Recov[300 MB],
B. Partition 1 [3-4 GB] probably where the Ubuntu OS /Ubuntu Setup was on and
C. Partition 2 Free/Unallocated Space [Rest of HDD])

Now everything worked correctly until just after completing the installation I discovered I accidentally deleted OEM Recv Partition also.

And afterwords while I was Installing Ubuntu from USB (bootable drive), the Ubuntu installation did not detected the Windows 7, (even though if I normally boot /Switch On my laptop, laptop was normally and correctly loading Win 7 and also showing C Drive (OS) and other drives (that I created, just after Win 7 installation was complete.)

Now my problem is

1. Can I get the OEM Recovery partition back? does this mean that I have to sent this laptop to the service centre of Dell OR Dell will provide some CD that will do the work.




2. Does deletion of OEM Recovery Partition is causing the problem of not showing the Win 7 as OS while installing Ubuntu 14.04 LTS

Please help me out here, I really want both systems on my laptop. If further info needed, do tell me !

Note: --My laptop came with Ubuntu 14.04 Pre-Installation Setup. So is OEM deletion is really the problem?
I just checked my partition is not Dynamic its basic only.

Also the Laptop was on UEFI mode (from where the boot option was Ubuntu) & not on Legacy. B4 installing Win 7 I changed this to Legacy

Solution:

(Basically it was GPT data left of the [then] existing Pre-Installation Setup Files of Ubuntu that the Laptop came up with, following instructions helped to clear those [1st two Links]. Then Installed Ubuntu (correctly shown the existing partitions; installed on partition created from free space), then just to make sure Windows 7 boots properly installed-updated-repaired the Grub [3rd Link]

No PARTITIONs found while installing, dual-boot Win8/Ubuntu 14.04

GPT partition table warning message during install of ubuntu

https://help.ubuntu.com/community/Boot-Repair#Getting_Boot-Repair

Also interesting to note that OEM Deletion was not problem. (Even though its mistake & a horrible one for Systems with Pre Installed/ Setups of OS other that Open Source) But like @Elder Greek said, my laptop came with Ubuntu & not Windows, so i was saved.
The problem was deletion of a partition where the Ubuntu setup file were existing, that left some GPT data on HDD even after deletion.

PS: Thanks to all those who tried to ans to my question without a fuss !! :)