You wish to find "hidden items on document page" or in your "entire document"?
If it is "hidden items on document page" do the following:
1. Goto the desired page from the pages panel
2. Open the layers panel
3. There you can see the items that are hidden
You need to toggle these control to hide/unhide items.
If it is "hidden items on entire document" do the following(I guess this is an easy way):
1. Open Preflights panel (windows menu->output->preflight)
2. Define a new profile
3. Enable the following entry
4. Click "Save"
Now you will see all hidden items with the page they are on. Double clicking on the page number, would navigate you to that page
You can read more about preflighting here Preflight files in InDesign before handoff to a service provider
Hope this helps:)
what would you like to do with the hidden frames?
Make them visible in one go?
1. Scope is the whole document including master pages and pasteboards:
app.documents.pageItems.everyItem().visible = true;
2. Scope is all document pages without master pages and pasteboards:
app.documents.pages.everyItem().pageItems.everyItem().visible = true;
If you want to turn on visibilty of all layers as well add this to the code:
app.documents.layers.everyItem().visible = true;
If you never worked with ExtendScript scripts see this:
I would go with simple way given. not comfortable with advanced InDesign.
Thanks to all