UE deleting assets by it self after restarting

Hello everyone,

I have a strange problem. I created a project based on the models from the Megascan. Everything was ok until today. After starting, the engine removed some models by itself, although I did not remove them. Before, everything was fine, it was loading everything correctly, including the models that now disappeared by themselves. The folder they were in is now empty. I can’t delete an empty folder because when deleting with right click or hotkey. After starting the engine the log window just shows the message “Faild to load mesh”. Please help