Well, this is a surprise! Your project is so "long" I cannot see the top of the layers list, or see which layer is selected so cannot determine it's positioning in time. Also, I don't see any corresponding groups in the timeline view and the canvas view images — that is a huge project!
Your time line Play Range is extraordinarily short. The playhead position is at frame 74, so the play range length looks to be about 90? frames, yet the entire project looks to be several minutes long. It does not look like there's a "master" group containing all other groups, so I don't believe the visibility has been toggled off.
Type the X key — do all the (supposed to be visible) layers appear in the canvas? (type it again to put things back).
Did you Solo a layer that is not active at the current playhead position? Finding a Solo'd layer that you forgot you soloed or soloed accidentally can be a pain... I think if you Select All layers and type Control-S will unsolo a lone layer.
Do most of the layers appear *under* a "blocking" layer (color solid set to black intended as a background?) Sometimes you would think that creating a new group somewhere in the list puts it in order, but Motion raises it to the top - adding graphics into it puts them all on top of everything else.
Check blend modes - anything with stencil/silhouette alpha or luma?
It's just really hard to determine what you've got going on here.