Samsung Galaxy S 2 (GT-I9100) Firmware Overview
What is the latest GT-I9100 firmware?
I9100XWMS2, released January 28, 2014 for region VOD with Android 4.1–4.3. The archive holds 2 official builds for this region.
Is the Samsung Galaxy S 2 still getting updates?
Most likely not: there has been no new firmware since January 2014, so Android 4.1–4.3 is the last version this model got. The final builds below are still the best choice for a clean reinstall.
GT-I9100 firmware for region VOD
How to Flash GT-I9100 Firmware
Put the Samsung Galaxy S 2 into Download Mode, load the BL, AP, CP and CSC files into Odin on a Windows PC and press Start. Use HOME_CSC to keep your data, CSC for a full wipe.