updated my iPhone 3GS last night to iOS 6 and found that if I click on any old text messages it gets deleted completely. The worst thing about this is my message thread with girlfriend was disappeared, and I needed to know her last message. Can anyone help me with this issue? I would appreciate it very much.

1. Resource from: http://www.video-converter-mac.org/recover-ios-6-message/
How to Recover Message Threads Deleted by iOS 6
Upgrade
I updated my iPhone 3GS last night to iOS 6 and found that if I click on any old
text messages it gets deleted completely. The worst thing about this is my
message thread with girlfriend was disappeared, and I needed to know her last
message. Can anyone help me with this issue? I would appreciate it very
much.
Text message threads, especially those business threads or those threads with friends, are important
parts of our daily life. Since iOS 6 update is available, many issues about data loss after the upgrading
happened. This is really annoying.Talking about this message threads loss issue, I would say, as long as
he has iTunes backup on his computer, he could still recover message thread lost after iOS 6 updating.
To resolve this issue, all you need is an iPhone data recovery tool which could extract iTunes backup file
from your computer. Wondershare Dr.Fone (Mac) (for Mac users) or Wondershare Dr.Fone (for
Windows users) is an effective tool to restore message thread with ease. Besides, the latest version of
Wondershare Dr.Fone (for Windows users) already supports data recovery directly from iPhone 4S and
iPhone 5.
Download the trial version of Wondershare iPhone data recovery tool below and start to recover
message threads from iPhone.
Two Simple Steps to Recover Message Threads from iOS 6 Device
S TE P 1 S C AN AN D E X TR ACT I TUN E S B ACKUP
After installation, launch the program, and you will have an interface as imabe below. iTunes backup files
of devices that have synced with your computer will be displayed, if you have only synced your iPhone
with iTunes, there would be only one backup file displayed. Choose your device’s backup and click “Start
Scan”

2. S TE P 2 RES TO RE ME S S AG E THRE AD S
An interface as below will be displayed in a moment. Files extracted from iTunes backup will be displayed
in categories, check “Messages” to preview the message threads you want to recover.
Choose message threads you want to recover then click “Recover” to save them on computer to read.
That’s all.

3. Notes:
1 Since this tool recovers data by extracting iTunes backup file, we suggest that you do not sync your
device with iTunes before you find data lost after updating to iOS 6, otherwise your previous iTunes
backup will be covered and you will not be able to recover old message threads.
2 Wondershare iPhone data recover tool is a useful tool to recover many kinds of files from iTunes
backup: messages, photos, notes, voice memos, videos, contacts, call history, calendar and more.
3 For iPhone 3GS and iPhone 4, this tool supports recovering data straightly from iPhone itself, which is
much more effective.