I can't get Wi-fi on my Iphone?

I'm running 3G 4.2.1 8GB on my Iphone i jeilbroke it ones but i didn't like it so I Restored it on Itunes sines then I still can't get WI-fi i can only get it when i'm right next to my talktalk box when i walk a way more then 3 setps a way from it i can't get Wi-fi and it's not my box I restored it again but Nuthing Again what can i do? Some help me out there

It sounds like the receiver in the iPhone isn't working correctly which would mean sending it to apple for repair probably. Does it work on other Wi-Fi networks such as McDonald's free Wi-Fi. Also, can other devices connect to your talk talk router from a distance away. If the answer to the first is no then it is likely it needs repairing, if the answer to the second is no then you know that the problem is your router.