why can't I connect my iPhone via wifii at my own home?

You could turn off encryption at your wifi router. The password would then no longer be needed - but that would also open you up to other people using your network. The "lock" just means that your iPhone sees the network but doesn't have the credentials to connect.

If you have a SBC router (the ones that have names starting with 2WIRE...) you can find the password (choose "HEX/ASCII key") on its back. For most other routers there's a way or two to reset the password. It'd help if you could tell me which router you own, for that, though :)

Set a new WEP or WPA key on your router and make sure that you add the MAC address of your iPhone, if your running MAC filtering. If you can't remember the password to the router,a admin console there is usually a reset button you can stick with a paperclip - check the manufacturers website.

Ohhhh! THAT's what the 2WIRE wireless networks are from!