Well, when I try to spend my balance, of course, it remains pending and is never mined in the blockchain.
It doesn't even fit into the mempool.
1. I hope that you made a backup of that wallet.dat
2. You should check on a block explorer (blockchair.com, mempool.space) if your addresses indeed have funds
3. If you have a very big number of small inputs then it can happen that your transaction gets too big (and expensive too). In that case you have to pick a smaller number of inputs and make multiple transactions.
4. If this doesn't work even with small number of inputs, you may need re-sync or (faster) import the relevant keys into Electrum and try from there. (Get Electrum only from electrum.org and
verify it)