Weird issue on baked lighting

Hello, first of all, sorry if it’s a stupid problem, i’m still a noob, so today I opened my project, and I could have the unpleasant surprise to find my scene completely destroyed, whereas when I closed it yesterday everything was fine, the present problems have absolutely no meaning for me, I’m looking and I don’t understand what’s going on, some objects are strangely lit, the skylight doesn’t seem to take the shadows anymore and sometimes I have some random crashes, when I didn’t have any before, would anyone have any idea what’s going on? Thank you.