I can not see the all the layers in liquify.

I am having this issue too. It seems to be a bug in v22 and higher, as when I attempt the same behavior in v21, it works.

Liquify only shows the current layer selected, regardless of your settings for Show Backdrop:

Okay, to see backdrop in liquify, then following the steps below would help

Select LIQUIFY from the FILTERS tab, on the properties tab, go to SHOW BACKDROP, Now set MODE to INFRONT. and make OPACITY 75%. Remember you won't see any change even after setting all these if your layers look exactly alike, without anything to differentiate then. You can work on one of the layers so you can see a difference when you select another layer.

You can checkout This tutorial on Photoshop LIQUIFY, it's very helpful.