Missing basic props?

Just started up Gmod today, having not had any problems of this nature in the past, to find I can’t spawn some very basic props. Props such as the wooden crate, blast doors etc… HL2 props? All those props that come with Gmod. Also getting ERROR signs in locations such as the skybox for construct.

Wondering if I buggered something up when installing mod / addons, or if there’s another reason why this is happening!

Thanks

What kind of things have you added?

A variety of things. Additional props, tools, one player skin…
The most recent thing I added was dinosaur props.

Bumping, still can’t find a solution