Then hopefully you saved it on a card or disc or usb elsewhere, preferably saved in a fireproof safe, encrypted.

Then you'd just need to find someone who has the blockchain themselves, or re-download it yourself and sync up. Very easy.

Or, as another poster said earlier, have it backed-up online as well. I personally don't keep large amounts of btc online through 3rd parties very long, but that's more of a personal preference these days.... many safe 3rd-party wallets out there