You are probably on the old PoSV v1 chain (Reddcoin Core v1/v2).
Solution would be to:
Make a backup of your wallet.
Update Reddcoin Core to most recent version (v3.10.3).
Delete existing blockchain data.
Resync (bootstrap to speed it up).
I can give you the instructions here and you follow them OR I can help you remotely via TeamViewer and I do the steps for you. Let me know what you prefer.
I assume you are using Windows. If not, let me know.
Open Reddcoin Core, and make a backup. Via File (menu) -> Backup wallet. Do not skip this step.
Exit/close Reddcoin Core, make sure it’s not running.
Press Windows Key + ‘R’ on your keyboard. The ‘Run’ window should open.
In the Run window, enter this: %AppData%
A new window with folders should open. Look for the ‘Reddcoin’ folder. Open the Reddcoin folder.
In the Reddcoin folder, delete the following folders:
blocks
chainstate
Delete the following file:
peers.dat
Do not close this window, leave it open.
Now, you need the downloaded file, the blockchain zip file. You should be able to extract the contents by right clicking on the file, and selecting ‘Extract all’… Do this, extract all the files.
A new window should open, the extracted contents should be visible. You should see 2 folders: blocks and chainstate.
Move the 2 folders (blocks and chainstate) to the other window that you left open, the Reddcoin folder window (where you deleted files from). To move, you can use CTRL+X-> CTRL+V.
Start Reddcoin Core.
Wait until the blockchain is fully synced.
When syncing is completed, your balance should be as expected.
Let me know how it goed. Don’t hesitate to ask questions.