How to fix my HDD that thinks that it has 20 GB when it really has 128 GB

Question

My dad screwed up my HDD while trying to install Ubuntu and Windows on separate partitions, so now it says it has 20.8 GB of space on the disk and it really has MUCH MORE, but I don't know exactly how much.

The computer is an HP intel celeron with 2.00 GB ram and 1.86 GB usable (don't know why that is).

Ubuntu never actually got installed and my dad installed Windows on the '20 GB' HDD and now Windows only thinks that's how big the drive is. Windows version: 1511.

There is no data that needs keeping, so I can delete everything if required. He partitioned it using Ubuntu installation disk, but then installed Windows! Come On!

The goal is to have both Windows and Ubuntu running stable on this computer and to fix the hard drive so it is 128 GB

I am 9 years old, hope this question can be resolved soon.

Answer 1

1. Boot to an Ubuntu live session (Try Ubuntu) from an Ubuntu live USB.

2. Launch GParted partition editor and reformat the 128GB drive as ntfs in order to overwrite everything that is installed on it. Now the Windows installer can recognize the drive.

3. Installing Windows alongside Ubuntu often breaks Ubuntu, so you need to install Windows first in an Ubuntu / Windows dual boot. Boot from the Windows installer and install Windows on the entire drive.

4. Boot from the Ubuntu installer and select the "Install Ubuntu alongside Windows" option. This option will automatically show you a drag-able partitioning slider and allow you to adjust the space allocation between the Windows and Ubuntu partitions.

5. After you have allocated space for Ubuntu, the Ubuntu installer will do everything automatically from there on. Just accept the defaults and let the Ubuntu installer do the work for you. To save time you can also let the Ubuntu installer install updates, device drivers and third-party codecs, so your new installation of Ubuntu will be ready to use as soon as the Ubuntu installer is finished and you restart the computer.

6. When the Ubuntu installation is finished the Ubuntu installer will prompt you to restart the computer. While the computer is restarting it will halt and prompt you to remove the USB Ubuntu installation media. Remove the USB thumb drive so the Ubuntu installer doesn't start automatically again.

In these steps I have selected the easy way to do everything skipping everything that is too complicated. Nevertheless there are some other things that you might need to know, and you can find these things at How do I install Ubuntu alongside a pre-installed Windows with UEFI?. You can skip most of it, but you will probably need to disable Secure Boot in the UEFI settings before you install Ubuntu.