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I use a TOSHIBA Satellite A300 laptop with Windows 8.1 Pro installed.
I made a live USB using Universal USB Installer 126.96.36.199 from which I can boot Ubuntu 15.04 using the ISO image from Ubuntu website.
My laptop successfully booted from the USB memory and ubuntu successfully ran without trouble.
On the desktop (I suppose it's called desktop) there was a file/program with the name "Install Ubuntu 15.04," which I opened.
During the installation I chose a drive which I already had decided to allocate for Ubuntu and changed its filesystem type to ext4`` and installed Ubuntu onto this drive. When the installation finished I was asked to restart my computer, which I did but instead my computer directly booted my windows 8.1.
The partition on which ubuntu is installed is now invisible to windows but it says "healthy" in the
Disk Management tab in the computer management window of Windows 8.1 .
I saw during the installation of ubuntu the status "Installing GRUB" or something similar, I did some research then found out that GRUB is a multiboot manager from FSF. However, it seems that it doesn't exist and I can't reach to boot Ubuntu installed on the HDD no matter what I do.
I'd like your help to know what I should do to:
Make my computer detect Ubuntu so I can boot it.
Ask each time for which OS I'd like to boot.
thank you very much