Why is my laptop don't have a Wi-Fi?

Don't worry about it, There's a very small side button on your laptop. So you should just turn on. After that you can connect your Wi-Fi easily.
I have also Lenovo keboard and I have faced this type of problem.

I believe lenovo has a software which manages all connections and stuff. If you have windows 7 or windows 8 or above go to the right end of the task bar and you will notice a fence(in increasing order) like icon. If you see that icon that means your laptop supports Wi-Fi. If not sometimes its hidden. In this case click on the arrow which is pointing up and click customize scroll and see if you have tht icon in there. If you do than indeed your machine supports Wi-Fi. But its not enabled from tht software which i mentioned before.

If your laptop have a Wi-Fi device than you just need to install this driver. You can find that software from lenovo website.

If your laptop doesn't have any Wi-Fi device than you can by a usb Wi-Fi adapter for your laptop its pretty easy and cool.

Call Lenovo support.