After Effects issue. Everything is white, not playing & new timeline in the comp box?

Creating a new composition by itself should not bear any effect on this, but who's to know? If it works for you and solves yoiur issue, then who would argue success? 🙂

Mylenium

So I just clicked this little button thats made of triangle, a circle and a square and everything has gone back to normal. Can some explain to me what happened?

Thank you

This typically indicates an issue with hardware accelerated functions, so check the relevant preferences section and update your system's graphics driver. Also check the same settings in the comp viewer and the preview panel just to be sure.

Mylenium