how to fix the tons of compilation errors?

When I try to make a new project, it brings me to safe mode with 468 ERRORS. All of them are “are you missing a using directive or an assembly reference?” ones. this did not happen the first time I tried to make a project. What happened? how do I fix this?

Reinstall all Unity.

If the problems appear from first moment, its the only thing you can do.

If you have projects, save the projects folders somewhere, unisntall unity and reistall latest stable version.

Bye.