Assure yourself, that your node wallet has been totally closed ("exit") and is not running in the background.
Go to your PUTinCoin wallet data folder (e.g. C:\Users\"YourWindowsUserName"\AppData\Roaming\PutinCoin), and delete the folders "database", "txleveldb" and the file "blk001.dat". (Do NOT DELETE the file "wallet.dat"! Otherwise your coins will be gone!) Copy the bootstrap.zip file you've downloaded from the below download link and unpack it in the PUTinCoin wallet data folder. Delete the bootstrap.zip (you don't need it anymore) and restart the wallet. Wait until the wallet has read the blockchaindata (this could take a while) and let it sync until the little checkmark is shown in the right bottom corner of the wallet window. Unlock your wallet for "staking" and PUT IN your coins! :-)