How should I handle entries in checking which must have been reconciled previously?

Rod F.

I've finished catching myself up, for 2020, in reconciling my checking account. However, I did something wrong with about two dozen entries from 2019, as they still appear unreconciled from 2019. I had thought they would eventually get reconciled, but they haven't. So, I'm guessing I've already handled this at some point in early 2020. Bottom line, I made a mistake somewhere.

Anyway, how do I handle those two dozen entries from 2019?

Sherlock

If the account register has been properly reconciled, these old unreconciled transactions have not cleared the financial institution.  You should review each of these transactions, confirm they have not cleared, and decide what you want to do about them.  If you expect them to clear eventually, you may leave the transactions in place.  If they are valid balanced entries that will never clear, you may mark them as reconciled.  If they're canceled checks you have voided, you may mark them reconciled or delete them.  In any case, you need to decide how you will handle them.

Sherlock

If the account register has been properly reconciled, these old unreconciled transactions have not cleared the financial institution.  You should review each of these transactions, confirm they have not cleared, and decide what you want to do about them.  If you expect them to clear eventually, you may leave the transactions in place.  If they are valid balanced entries that will never clear, you may mark them as reconciled.  If they're canceled checks you have voided, you may mark them reconciled or delete them.  In any case, you need to decide how you will handle them.

Tom Young

"If they are valid balanced entries that will never clear, you may mark them as reconciled."

Just to be clear, I think that @Sherlock is saying that if the sum of these transactions - some combination of payments and deposits - comes to $0 then they have no effect on your most recent reconciled balance and, accordingly, marking them all with an "R" in the "Clr" column won't affect your next reconciliation.  If, however, the sum of the subject transactions doesn't come to $0 then marking them with an "R" will affect you next reconciliation in that the opening balance for that reconciliation will be different than the prior ending balance.