I gave my Phone (Celkon A95) into a service centre because of touch malfunctioning before it I backed up the user data by pressing Power and Vol+ buttons, it gave me a backup file called userdata20130902_131223.backup. After a few days I got my phone back and when I restored the data it gave me "Checksum Error". I'm unable to restore my previous data. Is there any way get back at least messages and contacts?

Sorry for my bad english.

  • Had you synced your contacts with a Google account? If so they should all be backed up automatically.
    – Peanut
    Sep 17, 2013 at 22:11
  • so, what about messages..?? can i extract that backup file in pc..?? Sep 18, 2013 at 8:14
  • Maybe try extracting it using this: sourceforge.net/projects/adbextractor FYI I don't know how to import them back into Android and I've never tried the program so make a back up of the backup just in case it does something silly.
    – Peanut
    Sep 18, 2013 at 14:04

2 Answers 2


It's a 512 byte header in front of a "tar.gz"

hexdump -C userdata_xxxxxxxx_yyyyyy.backup | less

showed the magical zip header "1f8b0800 00000000" at offset 0x200 So, skipping 512 bytes, the rest can be gunzip | tar

dd if=userdata_xxxxxxxx_yyyyyy.backup bs=512 skip=1 | gunzip -c | tar xv

In the /data/ directory, hunt down the db file. It's a sqlite3 database file which you can view with a variety of tools, e.g. sqlitebrowser


Stock Android recovery backup files can be restored with a Nandroid custom recovery, if you simply repack them into tar archive.

i put this two command lines in a dirty shell script (extract + repack as tar). thanks to ektoric figuring out his gunzip method!

the shell script will convert your backup file into nandroid backup automatically. download >bckp2cwm.zip< at

From http://forum.xda-developers.com/showthread.php?p=65374561#post65374561

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