Aha! It's easy when you know how.
Your printer's IP address is probably assigned dynamically - meaning it could be different every time - by your router. Open your router's administration console (which you password-protected, right?) and look for the list of clients to find out what IP has been assigned.
If you want to reliably locate your printer by it's IP address, it's better to assign it a static - i.e., unchanging - IP address. This is also done in the router's administration console.
Here's another way to find the IP: Go to Control Panel and open Devices and Printers. Right-click on the printer's icon and select Properties. In the Properties sheet, open the Web Services tab and look on the bottom.
There are probably other methods, but the Russians may be watching this forum.