first of all check whether its s5260 or s5260n...............rest guide is here.. 1. Run Samsung S5260 Star II Downloader.
2. Check BRCM2133 option.
3. In case you want to flash Boot files to your phone check Full Download option.
4. Click Boot button and show the program the Boot files folder.
5. Click Apps button and select this file: apps_compressed.bin
6. Click Rsrc1 button and select this file: Rsrc_S5260_Open_Europe_Common.rc1
7. Click Rsrc2 button and select this file: Rsrc2_S5260(Low).rc2
8. Click Factory FS button and select this file: FactoryFs_S5260_Open_Europe_Common.ffs
9. Click CSC button and select this file: CSC_S5260_Open_Europe_Common_*.csc
10. Click SHP APP button and select this file: ShpApp.app
11. Put the phone into download mode: Press Hold key + Volume up key + Send key
12. Connect USB cable to phone and click Port Search button.
13. When the program detect the Com number that the phone takes click Download button to start the process.
14. Do not touch the phone or cable till all is done and the phone restart.
15. After reboot the phone you can do full reset by this Code: *2767*3855#.