I installed ubuntu 12.04 using wubi on windows 7 for dual-boot, now i dont see windows option while booting. It directly boots only ubuntu. What should i do to get the dual boot option window?
The programme taking care of that is GRUB. You can enter GRUB by holding Shift when the computer is booting. There you should be able to select either Windows or Linux.
If you want to always see the GRUB menu, consider changing the timeout, as is well described by e.g. this post on Linuxpoison