Well ofcourse it doesn't make sense. If it made sense you wouldn't be here asking the question aye?

Seriously though, the reason were having a hard time answering your question is your not wording it in a way that makes sense. And not to be blunt, but its probably stems from a basic understanding of networking on your part. Thats ok though, we can still help, we just need more information.
If your looking to reset your router back to factory, or how it was when you took it out of the box, hold down the reset button on the back with a toothpick or something small for about 10 seconds or so. Then let it sit for about 60seconds or so. Then disconnect and reconnect the power. Depending on how it is configured, you may also need to power cycle your modem as well before you power cycle your router. That resets everything though. Your SSID, your wireless security, and any other wireless settings you had configured.
As for your problem, I can make some assumptions. Limited or no connectivity was a error message that started with Vista, and it means it can talk to the router, but the router isn't talking back. Think of it like the door. Your computer finds the door, but the router won't let it through. The most likly cause is something to do with the wireless security, because that's like your computer key that it uses to get through the door. As for what is wrong with the key, I would first check to make sure your PC is compatible with what ever security method your using. Most important thing is if it can do AES. If it can't do AES you need to pick WPA with TKIP as your security while configuring it, but that may cause issues with other computers.
So yes, its pretty complicated. Thems the breaks.