It sounds like it's not connecting to the Internet at all.
Try changing your connection to "Wired", and then go back to "Wireless" and reselect your access point.
It would be rare unless it was bumped or bent, but it could also be the LinkStick has stopped working.
I've had my Samsung TV (Model no. LN52B750) for over a year and everything worked fine until this past week. Now I can't connect to any of the apps. My TV just says there is a problem with the connection and it cannot refresh the widgets at this time. I've performed the internet connection test and it is working fine. I've reset the TV to factory settings (as I was told to do by Samsung) and this did not help. I am using the wireless stick by Samsung.