I have windows 7 ultimate installed in my laptop. Yesterday I have installed ubuntu 12.10 using usb drive as dual boot system. after the successful installation of the ubuntu in a different partition i cant access ubuntu. when i start my laptop it's directly booting in to windows 7 and nothing showing in the boot menu whether i want to use windows 7 or ubuntu 12.10 After that when I have tried to install ubuntu again to check whether ubuntu successfully installed or not then it's showing the ubuntu is already installed. Please help me to recover this problem.