I have a Toshiba Satellite C55 Series Laptop. I decided to install Ubuntu because I love Android. When I installed Ubuntu there was a Windows 8 option, but after I restarted my laptop windows 8 option was gone. I have already tried a lot of things like sudo update-grub or sudo update-grub2. Can anyone help. Thanks
Install a package called "Boot Repair"
FYI: Boot-Repair is a simple tool to repair frequent boot issues you may encounter in Ubuntu like when you can't boot Ubuntu after installing Windows or another Linux distribution, or when you can't boot Windows after installing Ubuntu, or when GRUB is not displayed anymore, some upgrade breaks GRUB, etc.
Kindly follow up this link! https://help.ubuntu.com/community/Boot-Repair