Here is what you need to do:
When you boot up this will appear if Grub 2 was not able to find its folder or load a module:
(*Note "grub>" appears if modules were successfully loaded, but the grub.cfg file in the boot process)
You can type in "set" to see current setting.
To find out your partition table do:
They will be noted in a format similar to this: hdx,y (where x is the disk, and y is the partition - this might be relevant to you if you have more than 1 disk).
Find the partition with your Ubuntu/other linux installation and write it down to a piece of paper.
Do the following command, and input your partition:
set root (hdx,msdosy)
(eg. set root=(hd0,msdos3) or set root=(hd0,sda3) etc.. depends what you have)
We will now be setting the prefix, determining where is the boot folder. Usually it is one the same partition as your OS, so use that.
set prefix (hdx,msdosy)/BOOT LOCATION
(eg:set prefix (hdx,msdosy)/boot/grub)
Write this to load the normal module:
Now we attempt to activate the normal module. Grub 2 menu should appear if all went good. Write this:
After successfull boot to your OS, be sure to do the following in Terminal:
sudo grub-install --boot-directory=/boot/grub /dev/sda
Voila, you fixed your Grub 2. This is ofcourse much easier with a LiveCD, because the only thing you need to do is mount your filesystem and do the grub-install command.