Carrier unavailable after unlock

Hello i was wondering if anyone using this forum could help me. I recently attempted to unlock my iPhone 4 and now it will not accept any sim card.

I am not very technical and don't understand alot of the terms used in the threads here but i was shown a couple of videos from youtube on how to first 'jailbreak' my phone and then 'unlock' my phone and i followed them to the letter.

I did everything correctly to my knowledge, using 'Snowbreeze' to jailbreak it and then 'Ultrasn0w' to unlock it. Everything appeared to have gone well but then when i entered my new sim (On giffgaff network) it said 'No Signal' in the top left corner. I then re entered my old sim (On Orange network) and again it says 'No signal'.

I then looked at my phones settings and it now says 'Carrier - Not Available' and 'Network - Not Available'. Both had said 'Orange' before my attempt to unlock my phone.

I have since uninstalled the Ultrasn0w 5.1.1 fixer and Ultrasn0w itself and reinstalled it and still nothing. It is currently again uninstalled.

Does anyone know what i might have done wrong from this description? If anyone needs further information please let me know and i'll do my best.

Thanks a lot.