Password manager
Recovery may require emergency access features or master password from the vault or letter of instruction
Some steps differ by region inside the country.
Where
The password manager provider, using its emergency access or legacy feature. Their browser's saved passwords are a useful fallback.
How
Look for a printed recovery kit or emergency sheet, often kept in a safe or with the will.
Check whether you were designated as an emergency contact, which usually grants access after a waiting period.
Otherwise apply to the provider, though a truly zero knowledge provider may be unable to help at all.
Check saved passwords in the browser on their computer, which often works when the vault does not.
What to bring
A certified copy of the death certificate
Letters testamentary
Any printed recovery kit or emergency sheet
This is practical information, not legal, medical, or financial advice.