Do you have a backup of your wallet.dat and config files anywhere?

Here is what I would do, but I'm no expert either, so do it at your own risk - this is why everyone should backup wallet.dat often.  

copy the entire %appdata%/roaming/Sagacoin directory someplace else. Now, delete the whole %appdata%/Roaming/Sagacoin directory.

recreate the folder, add your wallet.dat and conf files if any.

Start the wallet qt.exe again, see if you can open your wallet and let it resync.

Edit- This can happen if you do not shutdown the wallet when you rebooted. You should always shut the wallet down clean before reboot.