Kill it in task manager, reboot.
Start it up, then go to changes and hit Refresh.
If that doesn't fix it, you may have to try using some Terminal commands
Working fine here. Do you have 3rd party repos? What error messages are you getting in Cydia?
You could run iCleaner and turn on the setting "Cydia Sources" and see if that fixes it. But proceed cautiously! I'm not responsible if it makes your problem worse lol