Rigging vanished from viewport but still exists in hierarchy

So for the last few pays I have been working on my blend file and ojbects disappear. By this I mean the still exist and are listed in the hierarchy but they won’t appear in the viewport. Also I cant change them from object mode like they are invisible but the hierarchy icon to make them visable is selected.
I woke up this morning to find that now the skeleton I made is affected and now I can’t finish animating.
How do I fix this?

Check they are on a visible layer
If bones, check they are not on hidden bone layers (in armature settings)
Check they have no modifier or constraint that would make them invisible
Check they are within the 3d view start/end clip distances (values in properties panel, shortcut N)
If looking through camera ensure they are within the camera start/end clip distances (values in camera properties)
Check they are within the viewport or camera view
Check the object are not hidden (outliner or unhide with Alt+H)

No blend file supplied with the question (a demo blend file should ALWAYS be included with ALL support questions !!) so we cannot check these things for you