Posted: Fri Jan 29, 2021 2:08am
As Steve has said above it's for life.
If you've got any bills, documents, agreements etc from your time in Spain that's the first place to look because your NIE number will definitely be on one of them.
If you live in the UK you might be able to retrieve it via enquiry to the Spanish Consulate. Just an idea.
If you live in Spain you can retrieve it and get a new hard copy by personal presentation at a National Police Station. Passport required. Fee payable at a nearby bank, then return to collect the certificate. Can be done all at the same time with good fortune!
Or, you could ask a Gestor in Spain if they can do it on your behalf and see what the answer is. I suspect it's no.
If your research is part of an application for Residency in Spain via NLV you may be interested to hear that it's been reported that an NIE number is assigned to successful applicants so they would find your number in that scenario I think.