What happened to multi-track view button?

Hello all,

There used to be two buttons for waveform and multi-track view button in the upper-left hand corner of my edit window, above the files bucket (see attached). Now they've gone and I can't seem to get them back. I've also lost the little icons for trim, razor, etc. 

It seems to be some kind of view setting that has changed, but nothing that I've done in view seems to bring themm back. Can anyone assist?

Many thanks!

-Adam