Data Recovery Techniques SS2 Computer Hardware & GSM Repair Lesson Note

Class: SS2

Subject: Computer Hardware and GSM Repair

Have you ever accidentally deleted a photo and felt your heart sink? Or maybe you formatted a memory card by mistake?

Here is a secret: When you “delete” a file, it isn’t actually gone immediately. The computer just hides it and marks that space as “Empty” so it can write something else there later. As long as you don’t save new files over that space, the “ghost” of your old file is still there. Data Recovery is the art of finding those ghosts and bringing them back to life.

Recovering from Memory Cards (SD Cards)

Memory cards are the easiest to recover data from because they are “Removable Storage.” We can take them out of the phone and plug them directly into a computer.

• The Rule of “Stop!”: If you realize you’ve deleted something from an SD card, take it out of the phone immediately. If you keep taking new photos, the phone will write the new data on top of the old “ghost” files, and they will be destroyed forever.
• The Software Method: We use special programs like Recuva, DiskDrill, or EaseUS Data Recovery.
  1. Plug the card into a PC using a Card Reader.
  2. Run the software and select the SD card drive.
  3. Click “Deep Scan.”
  4. Preview the found photos and save them to the Computer’s Desktop (Never save them back onto the same SD card during recovery!).

Internal Storage Recovery (The Hard Part)

Recovering files from the phone’s actual internal memory (the built-in 64GB or 128GB) is much harder than an SD card because of Android’s security.

• The Challenge: Modern Android phones use Encryption. This means the files are scrambled like a secret code. If the phone is factory reset, the “key” to that code is thrown away, making recovery almost impossible for a basic technician.
• The “Root” Method: For many deep recovery tools to work on internal storage, the phone must be Rooted. This gives the software “Superuser” permission to look into the hidden corners of the phone’s brain.
• Cloud Recovery (The Smart Way): Before you use a computer, always check Google Photos or Google Drive. Many phones automatically “backup” photos to the internet. If you find them there, you don’t need any complex software!

Physical Data Recovery (The “Surgical” Method)

What if the phone is physically smashed or won’t turn on? This is where a GSM technician becomes a surgeon.

• Broken Screen: If the phone works but the screen is black, we simply plug in a “Test Screen” to see the files and move them to a flash drive.
• Dead Motherboard: If the board is dead, we use a technique called Chip-Off Recovery. We use a hot air gun to remove the EMMC or UFS chip (the storage chip) and put it into a special “Socket” connected to a computer. This is an advanced and expensive skill.

Why Data Recovery Sometimes Fails

As a student, you must be honest with your customers. You cannot always save everything.

1. Overwriting: If the user kept using the phone for a week after deleting a file, the file is likely overwritten and gone.
2. Factory Reset (FRP): On new Android versions, a “Factory Reset” clears the encryption keys. Even professional tools can’t bring those files back.
3. Physical Damage to the Chip: If the storage chip itself is cracked or burnt, the data is lost forever.

Summary Table: Recovery Situations

Student Ethics & Privacy Guide

“Data recovery gives you access to a person’s most private life—their family photos, private messages, and bank details. Never look through a customer’s files. Your job is to recover the folder, verify that the files are opening, and then hand it back. Professionalism is about trust!”