If your computer is lost, stolen or damaged, or you accidentally delete your MultiBit HD information, then you will need to restore a wallet.
To restore your wallet and recover your bitcoin, you must have your wallet words.
With your wallet words, you can recover your bitcoin. You must keep your wallet words safe, because anyone who knows your wallet words can steal your bitcoin.
A wallet backup is an encrypted copy of your Bitcoin wallet. Provided you know your wallet words you can use a wallet backup to recover, in addition to your bitcoin:
If you followed the instructions in the getting started guide then you created a cloud backup service that continuously uploaded your encrypted wallet files to a server somewhere in the cloud. Locate the folder on your computer that is now a copy of your cloud backup folder.
If you don't have a backup but you do have your wallet words then you will be able to recover your bitcoin and any transactions present on the block chain. However, without a wallet backup, you will not be able to restore all the extra information such as contacts, notes, payment history, currencies and exchange rates.
From the unlock screen click the "Restore" button and follow the instructions on the MultiBit HD screen.
Because if you could, anyone could. If your cloud-based backup leaked out of the cloud and onto a thief's computer, the thief could steal all your bitcoin.
To restore your wallet, and recover your bitcoin, you must have your wallet words.
Sweep your bitcoin to a new wallet immediately. Don't delay. Here is the procedure:
An alternative and more private approach to a single "Empty wallet" would be to split your overall balance over several smaller transactions made to different receiving addresses from the new wallet. This would help to disguise your balance and allow you to test the process with smaller spends. The final spend should use Tools | Empty wallet so that an optimal miner's fee selection can be made and correctly zero your balance.
You can also use Manage wallet | Edit wallet to provide a note indicating that the wallet words are lost and you should avoid using that wallet for day to day use in the future.