Network and sharing center

Hi!!! I share the use of internet at home with another three computers via wireless connection. I have not been able to access internet recently. I have Windows vista and on the network and sharing center page map my computer appears connected to the computer where the router is connected but there is no connection between that computer and the internet. Also the computer where the router is connected has written bellow unidentified network instead of the name of the network that appeard before. The connection between my computer and the one that has the router is green and from that one to the internet is grey with a red cross over it. I clicked that cross to make an auto repair but it didn't work. Any explanation??? Thanks