I lost my 3G free internet on iphone5 after I reset my phone?

Yeah it's so wrong I had my plan including 3G and after I reset my iPhone, 3G still show at top corner on iPhone but wouldn't work, what's going on!

A factory reset removes All your files you have saves any text messages anything YOU put on the phone. So you need to back them up.

You will have to call YOUR NETWORK and request the INTERNET & MMS settings after a factory reset

In the UK this will be sent OTA as a text message which you then save (it does say "save" etc) It may even state make default you can say YES

Call and texts work straight away on inserting a sim card, the internet you need the INTERNET SETTINGS.
Theory over http://support.apple.com/.../kb/HT2283" class='ext_link'>http://support.apple.com/.../kb/HT2283

Now you know why they are sent as a text, in the UK on sim insertion (activation) many networks send it out immediately

In the UK this will be sent OTA as a text message which you then save (it does say "save" etc) It may even state make default you can say YES

As you already know from your question

Call and texts work straight away on inserting a sim card, the internet you need the INTERNET SETTINGS.
Theory over http://support.apple.com/kb/HT2283

Now you know why they are sent as a text, in the UK on sim insertion (activation) many networks send it out immediately ( Network locked phones have it pre installed before sold by the network)