Why can't my laptop find my network?

I can't connect to the internet on my laptop, it says the connection "isn't found." I've tried unplugging my router, restarting the laptop, making a new connection, everything. Also, I use the Wi-Fi on my iphone and it works just fine on that. It stopped working all of a sudden yesterday and it's still not working. It's an acer laptop with windows vista and a cisco router, if that has anything to do with the problem.

Troubleshoot network connection problems http://windows.microsoft.com/...n-problems

How to Ping an IP Address http://www.ehow.com/...dress.html

Have you by chance accidentally turned off the laptops Wi-Fi adapter? To check go and try to connect to a Wi-Fi, when it says can't connect, click on troubleshoot, it should state why it can't connect, if it says you need to unplus your router then that should be the problem, if nothing else works call the company you have internet from, and complain to him enough and they won't charge you for the house visit, and he should be able to fix your dilemma

Connect to the router with the ethernet cable
Open Device Manager - type it in start/search field the click on it
Click the + in front of Network Adapters
Double click the WLAN 802.11x device
Driver Tab
Update Driver
Let Windows Connect to Update the Driver

If your DSL/Cable Company sent you a disc, run it. It will connect you.

If you don't have one then
Find the name of your Network (SSID) from a PC that is wired to the Router.
Type http://192.168.0.1 or http://192.168.0.2 in the address bar of a browser.
Open Wireless section to get your SSID and WPA key.

Make sure WLAN Autoconfig is enabled in Services.
Type services.msc in run and click OK.
Scroll down to WLAN Autoconfig.
Set to Automatic and Start the Service.
Reboot and connect.

This problem can mean many things, odds are the problem is with the operating system itself. I'm going to give you some instruction of some things I would do if I was working on this computer.
Questions you should consider:
Do you get any error messages? If so contact Microsoft with the error message.
Is you computer under warranty? If so, it's best to let a technician handle the problem. Note: Sometimes they will reformat or replace your hard drive. You could loose all data so it would be a good idea to backup first.

Check online:
http://pc-freezing-tools.com/Automatically_Restart

Re-pare Steps:
1) Restart Windows in Safe Mode. As you computer is restarting, hold down F8 and once the menu appears, select Safe Mode using the arrow key and selecting by pressing enter. Note: If windows does not boot in safe mode then seek help from a train technician, the problem may be too complex to go into decision in the message.