Well, if you didn't actually make any payments, then I'm not sure that you need to track the payments you didn't make. They're already represented in the loan balance.
Probably all that need to be entered into the loan account is the monthly statement activity - which is just interest charges.
Of course, if you do that now, and date the interest expense in 2020, or anytime before your current tax period, then the interest won't be deducted from any year's taxes (unless you re-file or the interest was actually included on your taxes, though not on your financial statements.
If you didn't deduct the interest at the time, then note there is a GAAP rule that states you can record expenses in the current period when you discover them late - this year. If that is reasonable and applies, then record all the interest in the current financial/tax year and expense it this year.
