Linux

 ./smartcashd -reindex

Open your wallet folder, right click smartcash-qt.exe file and click on create shortcut. Now right click the shortcut file, click on properties and edit the field labeled as target.

By default it should be something like this: "C:\Program Files\SmartCash\smartcash-qt.exe"

To reindex the target field should look like this: "C:\Program Files\SmartCash\smartcash-qt.exe" -reindex

Once -reindex flag has been added to the end of the “Target” parameter, click apply and then OK. Now open this shortcut file to reindex your wallet. Once your wallet is fixed close your wallet and delete the shortcut file or you can keep it and use it whenever necessary. But do note that do not use these commands to open wallet every time. It is only to repair your wallet and once your wallet is fixed it is no longer needed.

Option2:

Right click on the desktop icon and go to properties.. in the target location after the "" type -reindex the start Smartcash.. be sure to remove it after you start because you'll reindex every time if its there.

macOS

1. Open Terminal program

2. Run this in Terminal 

cd /Applications/Smartcash-Qt.app/Contents/MacOS
./Smartcash-Qt -reindex