Apparently,none of the solutions in any other posts and forums worked for me
For some reasons I decided to remove ubuntu from my hard disk drive.

My partition table(presently):
(/dev/sda1) (fat32) 900 MiB ---(MBR,I suppose)
(/dev/sda2) (ntfs) 70 GiB -----(Windows 7)
(/dev/sda3) (ntfs) 314.88 GiB --(Personal File storage)
(/dev/sda4) (ext4) 80 GiB -----(Ubuntu 13.04)
(unallocated) -----1.31 MiB

So,after moving(cut-paste) everything(for backup) from the fat32 partition using win7..I booted into Ubuntu and copied the remaining 3 files(hidden in Win7 file explorer) -->bootmgr,bootsect.bak,and one more which I do not remember.TERRIBLE MISTAKE
After this I again booted into Windows and deleted ext4 partition..formatted it to ntfs..and shut down the pc.Then,I put in a Win7 bootable USB..using command prompt I entered bootrec /fixmbr,and bootrec /fixboot..
Restarting showed me the GRUB..choosing windows 7 showed me
"Disk Error. Press any key to restart."
I also installed a fresh Win7 installation on the 80 GiB partition expecting a Windows Legacy Bootloader with two win7 options..but did not work. Then..I used a Ubuntu LiveUSB to put it back to the present configuration(above) since all methods to restore the MBR failed..

I copied back the fat32 partitions backup files but couldn't copy those 3 files.Somehow ,they had been recreated and were non-replaceable.

I do not want to format the win7 partition for a fresh one.
I have used boot-repair..Restore MBR option brings back to "Disk error...." without even going through grub..so I reinstalled grub and I'm able to boot into Ubuntu.
grub menu shows the win7 option as "Windows 7 (loader) (on /dev/sda1)".

paste.ubuntu.com/5753710
paste.ubuntu.com/5775999