All my TF2 content has disappeared!

[Tutankabron]

EDIT: Problem solved, thanks anyway

Hi all!

I´m making a map for the first time. It was in part fully textured and detailed, but when I entered again in Hammer, all the TF2 textures and props had disappeared!
I only have blank brushes and error models. I only keep the custom ones.

What did happened?

Thanks

Tut