My hairdresser told me her father used liquid parafin on small balding patch on his head and it grew back. Is there any truth in this?

Paraffin is a substance made from hydrocarbons with many uses (treating hair loss not being one of them). I don’t know what your hairdresser is talking about.

I hope this wasn’t in the uk or south Africa – we mean kerosene when we say paraffin (language barrier to the US there!).
If it was in the UK I would hope he didnt smoke. Setting your head on fire may not be compatible with hair growth