Were you on a Gridcoin fork ? So, have you tried repairwallet yet ?
"After a few reports of peoples coins going missing or stolen due to a fork..." (see here)
So, go ahead and type in your Gridcoin wallet's !debug console:
You might see e.g. fields
- 'mismatched spent coins' or 'amount affected by repair'
then restart your wallet afterwards, and you should see your missing coins now.
If you just see:
- "wallet check passed": true
then all seems fine...