Was it F4? That would swap the layer switches (shy, fx, motion blur, etc) and the blending modes. You can also bring them back by using the small buttons in the lower-left corner of the Timeline.
I believe it wasn't f4, the problem is that the files don't appear in the timeline (so you can't cut them for example) but this is only in some files at the beginning of the video, the rest is normal
Ah, is it possible you've trimmed or moved those layers in the Timeline before the beginning of the composition? Try selecting the layers on the left, move the CTI to the first frame of the composition, then use the open bracket key [ to set their inPoints to the start of the composition.