All of my launchers keep crashing, my only fix is to factory reset. I need help for backing up valuable data
Basic walkthrough for any phone:



Alternative 1:


Flash a CWM recovery
For Samsung, use Heimdall. download for 'Galaxy S2' or 'SGH-i777', depending on what you own
Heimdall also supports a dump command that can be used to backup all flash beforehand
Command to flash: heimdall flash --recovery CWM-recovery.img
Enter the newly installed CWM recovery
Do a backup in CWM to your external sdcard (be sure there's enough space left)
switch off &amp; check the backup on your PC (it's located in /clockworkmod/backup/ on the sdcard)
If you're sure your backup is OK, enter CWM again and do a full wipe
Reboot your phone, do the first-time-init (Google Account and such)
Install Titanium Backup + its Pro key
in Titanium Backup: extract from nandroid backup




Alternative 2:


Applicable if your fastboot mode supports the extended command 'boot'  
Compatible devices: Google's Nexus Line, HTC Desire with patched HBOOT loader and others  


Steps:


Enter fastboot mode and load a recovery into RAM (without flashing): fastboot boot recovery.img
Continue with step 3 from 'Alternative 1'




Alternative 3 (Samsung only, but broken on Galaxy S i9000):

not tried yet, see this as an idea as for now. You're on your own with errors on extraction &amp; restore

Heimdall implements a 'dump' and command and a means to print the partition table (PIT):  

heimdall dump --chip-type NAND --chip-id 0 --output nanddump.out.img
heimdall print-pit or heimdall download-pit --output nand.out.pit

You may then cut the NAND dump into pieces (one for each partition) and name them accordingly. If successfull, you can then access your data and continue at Alternative 1, step 8 or 4