I have installed Ubuntu on my lappy alongside with Windows7 on DriveE (windows is in DriveC). when installing ubuntu it didn't ask any thing it ask only whether you want to install alongside with windows. I selected that option. there was message that installation was successful. After restarting it directly boots to windows it's not asking to select os and driveE which i have installed ubuntu is not visible.
please give solution to my problem
The problem is with the Linux bootloader (GRUB). Looks like it isn't installed correctly.
To re install GRUB you will need the live disk once again.
There are two ways,
Manual Method,
You can follow the great answer here - How can I repair grub? (How to get Ubuntu back after installing Windows?)
Though question is different, it is applicable for your case. In your case it should be sda not sdb as mentioned in answer step3.
Also Step 7 is must in this case.
Easier way,
You can use live disk & boot-repair tool to perform a Recommended Repair.
Instruction are here - https://help.ubuntu.com/community/Boot-Repair
At the end, it will generate a URL, please take a note of that URL. If after recommended repair, it doesn't load GRUB, please attach the URL in this question.
wubi.exe? or you are booting using a usb /cd – Web-E Apr 03 '13 at 05:53