Complete Guide to Reinstalling Ubuntu | For Beginners to Advanced Users

By 佐川 直弘 | Naohiro Sagawa (運営者)

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1. Introduction

Ubuntu is a popular open-source Linux distribution, but over time, the system can become unstable or experience issues due to configuration mistakes. In such cases, reinstalling Ubuntu can restore it to a clean state and help rebuild a stable and efficient environment.

In this guide, we will provide a comprehensive explanation of Ubuntu reinstallation for both beginners and advanced users, covering post-reinstallation setup, troubleshooting, and FAQs.

2. Preparing for Reinstallation

Before reinstalling Ubuntu, it is essential to prepare adequately. Proper data backup and selecting the right Ubuntu version are crucial for a smooth reinstallation process.

2.1 Choosing a Version (LTS vs Latest Release)

Ubuntu offers two main versions: LTS (Long Term Support) and Latest Release. Understanding their differences will help you choose the one that best fits your needs.

In general, if you prioritize a stable environment, it is recommended to choose the LTS version (e.g., Ubuntu 22.04 LTS).

2.2 Backing Up Your Data (Using Timeshift & Deja Dup)

Reinstalling Ubuntu can result in data loss, so it is crucial to back up important files beforehand.

Backup Methods

1. Using a GUI

• Use the “Deja Dup” (Backup Tool) to easily save your data to external storage or the cloud.
• Steps: “Settings” → “Backup” → “Select Backup Location” → “Start Backup”

1. Using the Terminal

• “Timeshift” allows you to create a full system snapshot.
• Installation Command:
  sudo apt install timeshift
• Creating a Snapshot:
  sudo timeshift --create --comments "Backup before reinstall"

2.3 Creating Installation Media (USB / DVD)

Download the Ubuntu ISO file and create installation media.

Steps

1. Download the ISO file from the official site

• Get the latest Ubuntu ISO from the official Ubuntu website.

1. Create a Bootable USB

• On Windows: Use the “Rufus” tool
• On Ubuntu: Use the dd command or “Startup Disk Creator” app
  sudo dd if=ubuntu.iso of=/dev/sdX bs=4M status=progress

1. Configure BIOS/UEFI to Boot from USB

• Restart your PC and change the boot order in BIOS (F2, F12, Del key).

3. Ubuntu Reinstallation Process

There are two main ways to reinstall Ubuntu: Standard Installation (Beginner-friendly) and Custom Installation (For Advanced Users).

3.1 Standard Installation (For Beginners)

This is a simple reinstallation method that completely wipes all data and performs a clean installation.

Steps

1. Boot from the USB Installation Media

• Start your PC from the USB media and select either “Try Ubuntu” or “Install Ubuntu.”

1. Select Installation Options

• Choose “Erase disk and install Ubuntu” (this will delete all data).

1. Set Language, Time Zone, and Keyboard Layout

• Select the appropriate keyboard layout (e.g., US or international).

1. Create a Username and Password

• Set up login credentials for the new Ubuntu installation.

1. Start Installation

• The installation will take a few minutes. Once complete, restart your PC.

3.2 Custom Installation (For Advanced Users)

This method allows you to maintain a dual-boot setup or reinstall Ubuntu while keeping specific partitions intact.

Steps

1. Select “Something Else” During Installation
2. Manually Configure Partitions

• Format / (root) partition
• Keep /home partition to retain user data
• Enable LVM or encryption (LUKS) if needed

1. Proceed with Installation

• Complete the language, timezone, and user setup as in the standard installation.

4. Initial Setup After Reinstallation

Once Ubuntu has been reinstalled, you need to configure some basic settings to optimize your system.

4.1 Running System Updates

After installation, it’s crucial to update the system to the latest packages. Run the following command to update everything:

sudo apt update && sudo apt upgrade -y

4.2 Reinstalling Essential Applications

After reinstalling Ubuntu, you will need to reinstall frequently used applications.

sudo apt install -y vim git curl

4.3 Setting Up Language Support

After reinstallation, Japanese input may not be enabled. Install Mozc (Google Japanese Input Engine) to set it up.

sudo apt install -y ibus-mozc

After installation, restart the system and enable Mozc under “Settings” → “Region & Language.”

5. Common Issues and Troubleshooting

After reinstalling Ubuntu, you may encounter some common issues. Here are possible solutions.

5.1 Ubuntu Installation Freezes or Stops

Possible Causes and Solutions

• Corrupt USB Installation Media
  → Verify the ISO checksum and recreate the USB boot media.
• UEFI/Legacy Mode Mismatch
  → Check BIOS settings and ensure the correct boot mode is selected.
• Hardware Compatibility Issues
  → Try booting Ubuntu in “Safe Graphics Mode.”

5.2 System Won’t Boot / GRUB Errors

If Ubuntu does not boot after reinstallation, the GRUB bootloader may not be configured correctly. You can repair it using the following steps.

GRUB Repair Steps

1. Boot Ubuntu from a Live USB
2. Open the Terminal and Run These Commands

sudo mount /dev/sdX /mnt
sudo grub-install --root-directory=/mnt /dev/sdX
sudo update-grub

※ Replace sdX with the correct disk where Ubuntu is installed.

3. Restart and Check if GRUB is Fixed

5.3 NVIDIA Drivers or Wi-Fi Not Working

Installing NVIDIA Drivers

sudo ubuntu-drivers autoinstall
sudo reboot

Fixing Missing Wi-Fi Drivers

sudo apt install firmware-b43-installer

After running this command, restart your PC and check if Wi-Fi is working.

6. FAQ (Frequently Asked Questions)

Here are answers to common questions regarding Ubuntu reinstallation.

6.1 Can I reset Ubuntu without reinstalling?

Ubuntu does not have a built-in “Reset” feature like Windows, but you can restore your system to a nearly fresh state using the following commands:

sudo apt autoremove --purge
sudo apt clean

Alternatively, you can delete everything except your home directory and reinstall necessary packages to return to a nearly default state.

6.2 Can I reinstall Ubuntu without affecting a dual-boot setup?

Yes, you can. When reinstalling, select “Custom Installation” and make sure not to delete the Windows partition.

6.3 What should I do if the Ubuntu installation fails?

• If you encounter errors during installation
  → Try recreating the USB installation media.
• If the system doesn’t boot after installation
  → Repair GRUB (see “5.2 GRUB Errors and Solutions”).

6.4 How can I restore data after reinstalling Ubuntu?

If you used a backup tool like Timeshift or Deja Dup, you can restore your files from the backup.

sudo timeshift --restore

6.5 Ubuntu is still slow or unstable after reinstalling. What should I do?

There may be hardware issues such as SSD wear or insufficient RAM. Use the following commands to check system performance:

top
iotop

To check SSD health:

sudo smartctl -a /dev/sdX

If hardware issues are detected, consider upgrading your system components.