Wifi on MacBook Pro suddenly stopped working
I have been using WiFi on my MacBook Pro for some time without any problems. Last week, I was connected on the WiFi and in the middle of a skype call - and it suddenly stopped working. After reboot - I was able to restart that evening. However, it has not worked since. Connections which were trouble free earlier have become completely out of reach. I am traveling - so the connections in the hotel etc. require code, but now the login screen never shows up.
I can see the network and when I try to connect, it comes up an exclamation mark through the WiFi icon after trying to connect. I am not a power user but had a colleague who has a lot of experience with MacBook Pro try but did not get anywhere. I have tried assist me, diagnostics, etc. (which seems to write a file but I do not have any use for it) but getting nowhere.
I need advice on where to turn. I am currently hardwired and can connect that way. Also, I can boot on Windows and connect there. I am running OS X 10.9.1. Will try and see if there is an update available.
Thank you very much!
MacBook Pro (Retina, Mid 2012), OS X Mavericks (10.9.1)