* make a backup of your current wallet and place it somewhere save, then close your wallet
* go to your backups folder inside your DashCore folder and copy one of those backups from there to the DashCore folder
* rename the backup (wallet.dat+date) to just wallet.dat
* start wallet with commandline option -reindex
If you have problems with downloading and syncing the blockchain then download the Dash bootstrap
from here : and place it in the DashCore folder (by default that folder can be found here : C:\Users\XXX\AppData\Roaming\DashCore).
This way you dont have the download the whole blockchain through the Dash wallet, you just have to sync it.
Deleting the peers.dat from the DashCore folder may also help with syncing the blockchain. After this, you can
recover the data after deletion.