The drop may still be ongoing, which would allow you to still reserve the POAP with an email address or mint it to an Ethereum address.
If your mint link or Secret is no longer working, there is a chance that the drop is still ongoing but has run out of POAPs to distribute. In some cases, the issuer may choose to distribute additional POAPs for the event so you may be able to contact them to request one.
If the drop has already ended, however, you will no longer be able to reserve or mint the POAP, unfortunately. It is always best to reserve or mint the POAP as soon as possible to prevent this. For reserving or minting, we recommend using our app (iOS, Android), as it's the easiest way to keep track of your collection and does not require you to enter your email or Ethereum address each time you claim a new POAP.