I had Ubuntu and Fedora in different drives in dual boot mode, but after I upgraded Ubuntu , the grub menu is not showing and directly boot into Ubuntu so I can't boot into my Fedora.
Any solutions, thank you.
Well, have you tried holding shift down while booting? It should display the Grub menu if Grub is installed.
I suppose it's also possible Grub got somehow removed but I don't think that should happen in Ubuntu upgrades.
Unfortunately I'm not a Grub expert, so if the above doesn't help, I can only point you to this Community Wiki page: