grub2 - How do I get the GRUB menu to show when starting my dual-boot system?

Recently I have installed Ubuntu 10.10 and selected a wrong option while installing it.

Now the problem is that my machine directly boots Ubuntu and even does not show me grub menu.

How do I install grub menu ?

And how do I add Windows Vista to the grub menu?

This is what I have tried.

sudo grub

> root (hd0,0)

> setup (hd0)

Error 17: Cannot mount selected partition

I don't know what's going wrong here and I am sure that I have not wiped out my windows partition.

Edit :

sudo update-grub

Generating grub.cfg ...  
Found linux image: /boot/vmlinuz-2.6.35-22-generic  
Found initrd image: /boot/initrd.img-2.6.35-22-generic  
Found memtest86+ image: /boot/memtest86+.bin  
ls: cannot access /media/BC54B2C654B282A6/boot  

Boot: No such file or directory  
done 

---

sudo os-prober

ls: cannot access /media/BC54B2C654B282A6/boot  
Boot: No such file or directory  

Thanks.

I tried using sudo update-grub and sudo os-prober but I had no luck.

So this is what I have done.

sudo gedit /etc/default/grub and placed a comment # in front of the line GRUB_HIDDEN_TIMEOUT=0.

Then I updated my grub so that I don't have to press Left shift for the grub to appear using sudo update-grub .

After updating the grub I opened grub.cfg using sudo gedit /boot/grub/grub.cfg command.

And added

menuentry "Windows Vista" {

set root='(hd0,1)'


chainloader +1

}

between ### BEGIN /etc/grub.d/40_custom ### and ### END /etc/grub.d/40_custom ###

And don't forget to save the file.

I am marking this answer as Community wiki in case someone wants to add or modify this post.

---

Edit to update:

Meanwhile (2013) we have a GUI tool to repair/reinstall grub: Boot Repair.

To use it, do one of the following:

• Create a live CD/USB of Ubuntu Secure Remix, which is an Ubuntu live with supplementary rescue tools, boot from that and use Boot Repair.




• If you already have a regular Ubuntu live iso, create live usb with UNetbootin, live boot from that and install Boot Repair

sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get
update

sudo apt-get install -y boot-repair && boot-repair &

(But apt-get update on a live USB might involve updates that take some time - and are also useless if the live usb is not persistent - so I recommend the first solution.)

Using Boot Repair to fix/reinstall GRUB is simple, just choose default/recommended repair option; more details here.