I dont get any updates anymore. The update windows is empty. I have also tried "sudo dpkg --configure -a" that have fix update problem before,with no luck... Please help..
There was some problem that messed up the update screen. Elementary released new updates that solved it. In particular, you need to install the latest packagekit package:
sudo apt-get update
sudo apt-get install packagekit
I don't know how to solve that problem but you can easily replace elementary's native "app centre" with some another app manangement software like Synaptic package manager. I am using it for a while and it is far better than the app centre. You could easily install it by running these commands in the terminal:
sudo apt-get update sudo apt-get upgrade sudo apt-get install synaptic
I had a similar issue last week and I was able to fix it with
sudo apt-get upgrade
It installed all the missing updates and now I'm able to install updates from app center again.