Makaila

I downloaded the launcher and got a few modpacks. After i finish playing them i closed the launcher but when i came back the next day i logged into the launcher and all of the modpacks were gone. I reinstalled the modpacks then launched then. When i got to the start screen i went to play in singleplayer and my world was still there. I click it and it says "Downloading terrain" then immediately says "shutting down" them takes me back to the start screen. I tried uninstalling and reinstalling the technic launcher but that hasn't helped. This has happened three times so far and it happens randomly. Please help.