You must ask the owner if you want to copy a 'creative work', eg
- a diary
- a photograph
- a film
If you don't know who the owner is you might need an 'orphan works licence' to copy the work. You should:
See if the work is covered by copyright - if it isn't, you don't need a licence to copy it.
Read the copyright exceptions - if the work is covered by an exception, you don't need a licence to copy it.
Check if the work is covered by the EU Orphan Works Directive - you won't need a licence if it is.
Do a diligent search to see if you can find out who owns the work you want to copy - read the guidance on how to do a diligent search depending on whether it's a literary, still visual art or film and sound work.
Apply for a licence if the work isn't covered by an exception or the EU Orphan Works Directive or you can't find the owner - read the orphan works licence guidance to find out how to apply for a licence.