no wifi in network in window

Bought a new imac os sierra unfortunately in network window there is no wifi on the left hand side which mean i can not set it up for wifi , is there anyway i can get this back, simply pressing the + window brings up another window- select the interface: thunderbolt bridge

i am most confused

If there is no Wi-Fi icon in the System Preferences > Networking window, then, either the Wi-Fi card is dead, disconnected, or missing. I would call Apple immediately. Did you buy it directly from Apple, from an Apple Store, or from another retail chain?

i bought it from a retail store, the wifi icon was there but could not connect to wifi i followed the some instructions online and was after only doing that the icon disappeared.

@Flyster

Welcome.

As it's an iMac: use an Ethernet cable to connect your Modem direct to the Ethernet port on the back of the iMac.

When you do that, can you go into System Preferences > Network and see if the Ethernet connection is shown on the left - usually it is at the top of the list.

By the way, as a general rule, an iMac, being a Desktop computer and usually kept in one place is best served via Ethernet cable than (over the air) WiFi.

Please post back.

Ian

What instructions did you follow? I do not advise you to follow instructions online other than those provided by Apple, unless you know what you are doing.
WiFi setup is pretty simple but if you need assistance simply click on the "Assist Me" button at the bottonm of the Network Preferences window.
If you cannot remember what you did then you will need restore the original preferences.
This can be done by starting up holding the Command + R button.
In the window that will appear choose reinstal OSX.
This will re install the operating System as it was. BUT it might be worth running First Aid from Disk Utility found in your applications folder first.
Select the Macintosh HD from the sidebar menu in Disk Utility and press First Aid. Then chect to see if the WiFi option has returned to Network preferences..

Assuming this is a new iMac you should have setup the WiFi preferences as part of the setup process. Did you not do that?
This is part of the setup because this also enables you to register the device with Apple and setup an Apple Account if you do not already have one. It also allows you to setup iCloud Services, a user (Admin) password etc.