I was playing with Debian Jessie, installed it on a USB drive and (almost) everything was ok.
In the end I noticed the original Grub (in the laptop's SSD) was over written.
I'm able to login into Ubuntu 15.04, which is installed in the laptop SSD via the new Grub, actually installed in the USB. In other words, now I need the USB inserted to boot into the old system.
I would like to be able to log into the old system without the USB, using the Grub installed in the laptop's SSD.
Question, how to repair Grub?
P.S.: I was used to do this kind of thing in LILO, just a matter o executing lilo. But Grub is kind of new to me.