I'm missing all transactions from 9/3/22-12/31/22

If the transitions are truly missing from the register then it would seem that restoring them would fix the balance rather than mess it up.

But before we talk about how to restore transactions, are you sure you don't have a filter set in the register that is making them hidden. Is there a green Clear Filters button at the top of the register? Is this occurring for just one account? Do you have that one account selected in the sidebar?

Do you have a backup that you can restore to check if the transactions are there. If they are, there is a way to extract those transactions from the backup into your current file so you don't lose the work you've done since the backup. It's a bit complex, so I won't go into it now unless it's needed. Also, if you restore a backup, make sure you have a copy of your current file stashed away so you can easily go back to the current.

Most banks allow download of transaction back 90 days. But if your Quicken file thinks the transactions were downloaded once, they won't download again. To get around this, you could create a new file with just this one account and download. This would at best only get you back to mid-november though.

Another option is to see if your credit union provides the ability to download transactions in Quicken (QFX) format. If so, you could download that file for the missing dates and import it into your current file.