I have installed Ubuntu using wubi in Win 7. When I restart my computer it is not showing the list of ubuntu in the list of operating system. I have checked in My Computer->Properties->Advanced->Under Startup and recovery Settings->time to display operating systems is 10 seconds. Am I doing something wrong?
Since you used Wubi, Ubuntu will appear in the Windows boot menu. Press F8 when booting Windows and you should see a menu similar to the image below:
Select Ubuntu and you are done. Very different from actually installing Ubuntu from the LiveCD where you would have the system completely separate from Windows. For example if something happens to the Windows system like a virus, corruption, boot error, etc.. any problem that eliminates the possibility to boot windows then you will be left temporally without Linux or Windows.
In the case of the LiveCD installation like the image below:
It is less prone to virus/corruption problems.