I bought a iphone off my friend 3gs 16gb but she got it from hong kong. Anyway it worked fine but its network locked.

So i used the redsnow jailbreak teathered version for 4.2.1. And i changed the base band to higher one. But funny it never unlocked it, the only thing i did was when jailbreaking it was putting on cydia and thats it.

So it didn't work i went to delete everything off the iphone and reset all settings.
When that happen it rebooted to apple logo and had that line from underneath the progress sign. But it never moved for a whole day.

So i put it in DFU mode and try to restore it with the custom firmware but i get a code 21 every time when i do it.

What am i'm supposed to do i can't fix it.