Upgrading should not have that effect. Downgrading may cause that effect. Generally the cause for that happening is not closing LW down fully before shutting down the computer or your comp crashed whilst LW was still open.

There's no answer for starting them from where they were. But at least you can start them over. But they will start from 0%. Go to LW's Library window & select the incomplete folder. Then select the files & press the Resume button. This will force them back into the downld window & they will attempt to downld again. Sorry to hear this happened to you.