Macbook Air won't detect Apple TV or wireless printer

I purchased a Macbook Air with Mavericks a couple of months ago and had a wireless HP Photosmart printer, which I set up on the macbook. The machine recognised it over the wireless network and then all of a sudden one day I could not print to it. So I removed it to try a reinstall and the macbook would not detect it again after that. I have had to buy a cable to physically connect the printer to the machine when I need to print or scan.

Then I recently got my hands on an Apple TV a couple of weeks ago and it is working fine on the network, I can mirror the iPad on it but when it comes to the macbook, the Airplay Display is showing "No device detected". However, when I open iTunes and all of the Home Sharing is enabled etc (I have followed all of the guidelines to enable all of the settings for sharing ...), I go into Computers on the Apple TV and it attempts to load my iTunes library for a couple of minutes, after which time it says it could not connect.

I'm basically wondering if there is some setting on the macbook that I can't find that may need to be changed to allow me to see devices over the wifi at home.

I've been looking for a while but may just be looking in the wrong places. Any help appreciated for an Apple Noob