Lost Life in the UK pass letter

Hello,I passed my life in the UK test in 2015,but Now I have lost the letter.I have checked my email,but there
are no reference number or ID number.It's only assessment confirmation date.
- How can I receive a replacement certificate,letter or recover test reference number,please
- I shall need it for my ILR and naturalisation applications.

Thank you.

Do you have a copy of it or not?

If you don't have a copy, you will likely need to redo the test as it is mandatory for both ilr and naturalisation.