Whats the problem when wi-fi works and lan does not

did it just die on you? did you reload windows?

Usually on laptops, it's either one or the other and not both. There should be a button or slider somewhere to to disable the wireless functionality.

all you need to do is connect an ethernet cable that is connected to a working router, and make sure you don't have static settings that would inhibit connecting to the attached network

Some reasons why a wired connection may not work (even if wireless does) include:
LAN Adapter disabled in BIOS or in Windows
Bad cable
Bad router port, OR router configuration issue. ipconfig may give some insight on this.
Missing drivers (! or x may show in Device Manager)