Settings changed? No IPv4 internet access & "Default Gateway N/A"

Hello! I have a Dell laptop, running Windows 7. Yesterday my cat walked across the keyboard and literally that very moment, my internet lost connection.

It wasn't a case where she disabled the wireless capability by pressing the combination of fn and F2. The wireless is turned on, and is in face connected to the wireless network.

The troubleshooter said that the problem is that "default gateway is not available." Also, when I look at the network's properties, IPv4 Connectivity says "No internet connection."

I did a system restore to the night before and nothing changed.

I also tried resetting the IPv4 by entering "netsh int ipv4 reset reset.log" on the command prompt but this did not fix anything.

This afternoon I turned on the laptop again and for a split second, it said I had internet access but the yellow exclamation point came up quickly and I no longer had it.

I am on my old laptop right now and the connection is just fine, and it's also working for my roommate's computer.

Does anyone know how I might be able to fix this? Many thanks in advance.