Recover the known structure
Preserve the edited tree for diagnosis and compare it with the saved baseline belonging to the installed release. Check whether the required default files were copied along with the new node. Confirm actual userdata paths rather than using a historical platform example blindly.
Restore the recorded known structure when necessary, then inspect the old routes and the proposed new route separately. Cleaning the media library or deleting source files would change a different layer and can make a simple navigation error harder to understand.
Reapply one small change
Once ordinary navigation is back, introduce only the intended node edit. Verify entry, content and return navigation in the actual skin. Record the changed file and release so a future upgrade review has a concrete comparison point.
Questions answered
Does a missing Movies entry automatically require a library rebuild?
No. Review the custom navigation structure and the last change first.
Can I copy an old operating-system path without checking it?
Confirm the actual installed defaults and userdata location for the current setup.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.