Changing your ip address windows 7

Nothing really.

Are u running any web page, ftp, ...?

your internet will go down for a few seconds to a few minutes but that's trivial

If it's not on the same subnet as your router and other devices, it won't be able to communicate or get on the internet.

It depends what you mean by "change your IP". Generally, your ISP will assign an IP address to you.

If you mean changing the local IP address of your computer then nothing will happen if you change the last set on numbers (unless it conflicts). If you change the other ones then it will not be able to access the network.