Are you jailbroken? I unfortunately can't test right now, but I have used TetherMe to share 3G via a Sync Cable to my laptop. If I have 3G disabled it's definately conceivable that it with tether your wifi data in place of 3G.
It's obviously just a really unusual request. I'm assuming it's only a temporary solution.
That's not the question.
The OP does NOT have a data plan.
The wifi broke at home from what I can understand.
So in other words no you cannot get internet at home to your iphone without wifi. Where would that signal come from? You cant plug in an ethernet wire to your iphone can you?
Get a new wireless adapter for your computer.
Read the OP's post more carefully. He is essentially saying that he wants to use his iPhone as a wifi card for his computer which has a broken wifi card... I.e. like you can do with an Aiport Express.
In other words, my post has been the only relevant one so be helpful or shush.
Op states he does not have a data plan on the iPhone.
If your computer's wifi adaptor is broken, how do you plan on getting the data from your phone to your computer? Magic?