I have the 3rd gen Apple TV and it just will not conect to my laptop, can anyone help ?

The following article(s) may help you.

Understanding Home Sharing

Setting Up Home Sharing On A Computer

Troubleshooting Home Sharing

Troubleshooting Wi-Fi networks and connections

Recommended Wi-Fi settings

Wifi Diagnostic Software (for Mac users)

You may also find some help on this page, where I’ve collected some of the more unusual solutions to network issues.

Is it not being detected or is there an error?

If it's the detection, are you following the steps exactly? Disconnecting all cables, plugging in micro USB and then reconnecting power.

http://support.apple.com/kb/ht4367

• Check that you have correctly followed the instructions for your model of Apple TV (See below)
• If not already, try using a powered USB port.
• Repeat the process but this time try connecting the cable while iTunes is closed.
• Repeat the process with another cable.
• Try restoring the Apple TV on another computer in another location.

Get yourself a micro USB cable (sold separately), you can restore your Apple TV from iTunes:

1. Remove ALL cables from Apple TV. (if you don't you will not see Apple TV in the iTunes Source list)
2. Connect the micro USB cable to the Apple TV and to your computer.
3. Reconnect the power cable (only for Apple TV 3)
4. Open iTunes.
5. Select your Apple TV in the Devices list, and then click Restore.