A general problem for new bee’s is loss of grub during os installation
its very simple to resolve the problem as follows :
Boot into the live Ubuntu cd. This can be the live installer cd or the older live session Ubuntu cds.
When you get to the desktop open a terminal and enter. (I am going to give you the commands and then I will explain them later)
This will get you a “grub>” prompt (i.e. the grub shell). At grub>. enter these commands
This will return a location. If you have more than one, select the installation that you want to provide the grub files.
Next, THIS IS IMPORTANT, whatever was returned for the find command use it in the next line (you are still at grub>. when you enter the next 3 commands)
Again use the value from the find command i.e. if find returned (hd0,1) then you would enter root (hd0,1)
Next enter the command to install grub to the mbr
Finally exit the grub shell
That is it. Grub will be installed to the mbr.
When you reboot, you will have the grub menu at startup.