I received this used laptop Y550 a few days ago. When I got it, the wifi worked well. One day, it stopped working therefore I re-installed Window 7 (Lenovo recovery CD).
Whenever I switched on the physical wireless button, it just doesn't do anything. No wifi signal at all. Here's what I tried so far:
1) Updated the driver and BIOS (Intel Wifi link 5100 AGN)
2) When setting up my Network and Sharing center, and whenever I tried trouble shooting, it says "Turn on wireless capability"
Should I change the wireless card?
In addtion to the physical switch, make sure you activate wireless card by pressing Fn + F5 on keyboard.
When you press Fn + F5, Lenovo Wireless Device Settings windows will show up. Make sure you select "on" for wireless. Image below shows the wifi card is already turned on.
Note: Check if your Fn keys work, otherwise re-install Lenovo Energy
Management both software/utilities and drivers. There is a Hotkey driver
in Lenovo Energy Management package. The hotkey is to enable the Fn