It does not matter if handrails were ever installed at the property. It does not matter if handrails were once installed and are now missing. It does matter if handrails are present but damaged. Missing, non-existent or damaged handrails are a safety issue so handrails must be installed. Regardless of the circumstances, you as the contractor are now responsible for insuring there are no safety issues concerning handrails.
If you notice that handrails were never installed where they should have been, document that fact with plenty of photos. Take photos of all steps, staircases and stairwells. If your photos reveal that there were no previous screw or bolt holes or any other visible method to mount handrails, the photos should be sufficient to prove this. However, you are now responsible for correcting the safety issue by installing handrails. Unless given prior approval, you will need to bid for installation using the photos as your documentation.
If handrails were never installed but needed – install if pre-approved, else bid to install.
If handrails were installed but are now damaged – repair if pre-approved, else bid to repair.
If handrails were installed but are now missing – install if pre-approved, else bid to install.