On Windows do the following :
Create a shortcut to the Syscoin-QT.exe by right-clicking on the exe file. Then select “Send to” – > Desktop (create shortcut). Go to your desktop, right-click on the shortcut you have just created and select Properties. Make sure you are on the Shortcut tab. Then under target add -salvagewallet to the end of this.
Should now be C:syscoinSyscoin-Qt.exe -salvagewallet
Click OK. Then run the QT-wallet again using the shortcut.
Remember to remove the -salvagewallet after the wallet has been fixed.