If my passport expired over 15 years ago do I renew or apply for a?
The rules are specified for different countries. In India you have to apply for a new passport if more than 3 years have passed since expiry. Otherwise it can be renewed. Even if you are applying for a new passport you will have to give details (at least a photocopy, if not originals) of your old passport. For the UK it seems to be 5 years. Check your countrys passport departments website.