Mission bug "casinò Silver coast: infiltration"

Hi,
this is what happened: while doing the "casino silver coast" mission of the "citadel" dlc, i had to talk to a guard and while the game autosaved, but when i got close to the guard he disappears and the screen changed color slightly , I walked away and the game told me to go talk to the guard and re-saved, but every time I got closer the guard disappeared and the screen got weirder and weirder. I exited the game and came back in, the game automatically loads the last save, i.e. the autosave, but the screen is black after loading and I can't even access the menu, I can't do anything.
I already contacted the support service but they didn't help me practically, I would like to know if it is possible to load a save before the autosave.

I haven't an error message, after the loading the game starts but the screen is all black and nothing works.

it's not a pc issue, i had no problem during the all game. It all started in that moment and i have read that is a bug that happen when you use the slot machine during that mission, unfortunately i used them and than the game stop working. Without recovering the old save files i can't play anymore.
Thanks