How to Reinstall Ubuntu: Complete Beginner & Advanced Guide (Backup, Installation, Troubleshooting, FAQ)

1. Introduction

Ubuntu is a popular open-source Linux distribution, but after long-term use, the system may become unstable or encounter issues due to configuration mistakes. In such cases, reinstalling Ubuntu can restore the system to a clean state and help you rebuild a stable and comfortable working environment.

This article provides a detailed guide on how to reinstall Ubuntu for both beginners and advanced users, and also covers post-installation setup, troubleshooting, and FAQs.

2. Preparation Before Reinstalling

Before reinstalling Ubuntu, it is crucial to prepare properly. In particular, backing up important data and selecting the appropriate Ubuntu version are essential for a smooth reinstallation process.

2.1 Choosing a Version (LTS vs. Latest Release)

Ubuntu offers two types of releases: LTS (Long Term Support) and the latest non-LTS releases. Understanding their characteristics will help you choose the version that best fits your needs.

In general, if you want a stable environment, choosing an LTS version (e.g., Ubuntu 22.04 LTS) is recommended.

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

Reinstalling Ubuntu may erase existing data, so you must back up important files beforehand.

Backup Methods

1. Using a GUI Tool

• With the “Deja Dup” backup tool, you can easily save data to external storage or cloud services.
• Steps: “Settings” → “Backups” → “Select Backup Location” → “Back Up Now”

1. Using the Terminal

• By using “Timeshift,” you can create full system snapshots.
• How to install
  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 bootable installation media.

Steps

1. Download the ISO from the official website

• Get the latest ISO from the official Ubuntu website.

1. Create a USB installation media

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

1. Configure BIOS/UEFI to boot from USB

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

3. Ubuntu Reinstallation Procedure

There are two main methods for reinstalling Ubuntu: Standard Installation (Beginner-Friendly) and Custom Installation (Advanced Users).

3.1 Standard Installation (For Beginners)

This method performs a clean installation by erasing all data.

Steps

1. Boot from the USB installation media

• Boot your PC from the USB and select “Try Ubuntu” or “Install Ubuntu.”

1. Select installation options

• Select “Erase disk and install Ubuntu” (this completely deletes all data).

1. Language, time zone, keyboard settings

• Select the appropriate keyboard layout.

1. Set username and password

• Create your login credentials for after installation.

1. Start installation

• Installation completes in several minutes, followed by a reboot.

3.2 Custom Installation (For Advanced Users)

This method allows you to maintain dual-boot configurations or preserve specific partitions while reinstalling Ubuntu.

Steps

1. Select “Custom Installation” under installation type
2. Manually configure partitions

• Format / (root)
• Keep /home if you want to preserve user data
• Configure LVM or encryption (LUKS) if required

1. Other settings are the same as standard installation

• Configure language, user profile, and proceed with installation.

4. Initial Setup After Reinstallation

After reinstalling Ubuntu, perform the basic setup to prepare your working environment.

4.1 Running System Updates

Immediately after installation, it is important to update the system to the latest state. Run the following command to update all packages:

sudo apt update && sudo apt upgrade -y

4.2 Reinstalling Necessary Applications

After reinstalling Ubuntu, you will need to reinstall the applications you regularly use.

sudo apt install -y vim git curl

4.3 Setting Up the Japanese Environment

In some cases, Japanese input may not be enabled after reinstalling Ubuntu. Install Mozc (Google Japanese Input Engine) to enable Japanese input.

sudo apt install -y ibus-mozc

Then reboot your system, go to “Settings” → “Region & Language,” and enable Mozc.

5. Common Issues and Solutions

Here are common issues that may occur after reinstalling Ubuntu and how to fix them.

5.1 Ubuntu Installation Freezes or Stops

Possible Causes and Solutions

• Incorrect USB media creation
  → Check the ISO checksum and recreate the installation media.
• Mismatch in UEFI/Legacy boot settings
  → Adjust your BIOS settings to the correct boot mode.
• Hardware compatibility issues
  → Boot using “Ubuntu (safe graphics mode).”

5.2 System Won’t Boot / GRUB Errors

If GRUB is not properly configured after reinstalling Ubuntu, the system may fail to boot. You can repair GRUB using the following steps:

GRUB Repair Procedure

1. Boot Ubuntu using a live USB
2. Open a terminal and run the following commands

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

* Replace sdX with the disk where Ubuntu is installed.

3. Reboot and check whether GRUB has been repaired

5.3 NVIDIA or Wi-Fi Drivers Not Working

Installing NVIDIA Drivers

sudo ubuntu-drivers autoinstall
sudo reboot

If Wi-Fi Drivers Are Missing

sudo apt install firmware-b43-installer

After running the command, reboot your PC and verify that Wi-Fi is functioning correctly.

6. FAQ (Frequently Asked Questions)

Here are answers to common questions related to reinstalling Ubuntu.

6.1 Can I initialize the system without reinstalling Ubuntu?

Ubuntu does not have a “Reset” feature like Windows, but you can clean the system using the following commands:

sudo apt autoremove --purge
sudo apt clean

You can also delete everything except the home directory and reinstall necessary packages to approximate a fresh installation.

6.2 Can I reinstall only Ubuntu in a dual-boot environment?

Yes. During installation, select “Custom Installation” and ensure you do not delete the Windows partition.

6.3 What should I do if Ubuntu fails to install?

• If errors occur during installation
  → Recreate the USB installation media.
• If the system will not boot after installation
  → Repair GRUB (see “5.2”).

6.4 How can I restore data after reinstalling Ubuntu?

If you used a backup tool such as Timeshift or Deja Dup, you can restore your data from the created backups.

sudo timeshift --restore

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

There may be hardware issues such as SSD degradation or insufficient RAM. Check system load with the following commands:

top
iotop

To check the SSD health status:

sudo smartctl -a /dev/sdX

If issues are detected, consider upgrading your hardware.