Press a wrong button and you can accidentally delete all your contacts and saved information from your cell phone. Phones on the GSM network store this information on an internal smart card, also known as a SIM card (Subscriber Identity Module). Fortunately, the process can be reversed by connecting the cell phone's internal SIM card to a computer and using the correct recovery software.

Stop

Immediately stop using the cell phone. Saving data on top of a formatted SIM card can permanently delete the old data. As long as you don't continue recording information, you should be able to recover personal information such as text messages or contacts.

Software

There are plenty of options for recovery software. Read reviews first. Decide if it's worth paying for a full program. If you don't want to pay, there are some free options out there with limited capabilities that can do the job. Be careful. Downloading from a non-reputable site will put you at risk for viruses. Most software is capable of recovering data from several data storage devices such as camera memory cards and computer hard drives, so be sure to specify that you are recovering data from a SIM card.

Retrieve SIM Card

Turn off the phone before proceeding. The SIM card is usually located underneath the cell battery. Remove the plastic back of the phone and detach the battery. The SIM card is small and flat and usually has the manufacturer's logo. Use your fingernail to slide the metal holder that holds the SIM card and remove it from the phone. Insert the SIM card into a universal SIM card reader. Connect the reader to your computer---usually into your USB port. The computer should recognize the device automatically.

Fixing

Download and install the software on your computer. It will provide specific instructions on how to recover lost data. Once you start the program and have connected the SIM card to your computer, you can select the SIM card from the menu. You will be given the option to search for deleted data and save any information you want to the computer hard drive. From there you can manually re-enter contact information into your cell, or use another program to automatically transfer data back onto the SIM card. On the taskbar at the bottom right screen of windows, there will be a "safely remove hardware" button. Close the software program and click this button before removing the SIM card from your USB port. Re-attach the SIM card to you cell, replace the battery, and power up.

Source:

Data Doctor