Timeline quiry - i've lost part of it!!

Question

So on the top layer you have your layers of clips, for arguments sake lets say you have one.
The layer below you have your grades, up to four individual grades.
The layer below this you can mark in and mark out re: tracking.
The layer below this you can set your key frames.
In conclusion there are four layers but I can only see two = the clips and the grading layers.
The "mark in and mark out" layer is gone and the "keyframe" layer is also gone.
At the bottom left of the timeline there is sometimes a small triangle to shrink or enlarge the individual layers... this has helped in the past but this has gone too!!
Any ideas would be most appreciated.
T

Answer 1

Thanks for the reply. To be honest even if I mark in and mark out and then click onto another grade the necessary layer does not appear. I have only 1 grade and 3 rooms so plenty of space. I know it's there I just need to be able to pull it up.
Once at the bottom left hand side of the time line there was this triangle that I could pull and it would bring up the layers. (similar to enlarging the clip layer vertically in order to see the reference images clearer).
MMMMMm now these triangle have gone and when I try and pull the "hidden" layers up a yellow line appears.
Thanks for the thoughts T