I use Magnifier a lot, cause I watch my videos from my bed, and it allows me to see my file from there and choose the video I want to watch ...
I didn't tried a Backup, and it's too late for that now.
But I made a repair install and it didn't work.
As for the 3rd party apps, sadly none of them is this good
PS : Do not hesitate, if you want to answer to me on the two website, do not hesitate to simply make a copy/paste. And sorry again for that, but I have to post on a lot of sites if I want to find the answer. I hope you understand.