Can't save the project and attached a video to it

Hello all.
The problem started when I attached a video to the project, the project froze every time, so I updated the version of Cubase from 12.0.60 to 12.0.70, then I could attach a video to the project but I couldn’t save (in anyway)
I got the massage “this project could not be saved the system cannot find the file specified”, I restarted the pc and now I can’t do both. Please help, thanks.