This happens to most homeschooling families at least once, and almost nobody writes about it, because published advice is aimed at the version of you who kept up.
The good news is that more is recoverable than it feels like right now. The rest of it you can be honest about, which is a genuinely acceptable outcome.
What is actually recoverable
Work through these in order. Most families recover a usable picture of the year in an afternoon.
6 things to do
Ticks are for this visit only. Nothing here is saved anywhere.
Reconstruct honestly, do not invent
Write approximate dates as approximate. October to December, rather than a made up Tuesday. A record that says roughly when something happened is credible. A record with invented precision is not, and if anybody ever checks, the precision is what damages you.
Evaluators and reviewers are, in general, looking for evidence that education happened. They are not forensic auditors, and a clearly reconstructed term marked as reconstructed is a normal thing to receive.
Check what your state actually requires first
Before spending a weekend on this, find out what you genuinely need. Several states require nothing at all, in which case this is for your own use and can be as rough as you like.
If you are in one of the six that mandate a portfolio, the requirements are specific and worth reading properly. Both are covered in record keeping requirements by state.
Why it stopped in October
It is worth knowing, because otherwise it happens again in the second week of next term. Almost always the system was too heavy: a spreadsheet with nine columns, or a plan to write a paragraph a day about each child.
Anything that takes more than about a minute does not survive a bad week, and every year contains several bad weeks. The version that lasts records three things: the date, the subject and roughly what part of it, and one word about how it went.
Do not backfill the whole year before restarting
The common failure now is deciding to reconstruct everything perfectly before recording anything new, and then doing neither.
Start recording today, and reconstruct backwards in odd half hours. Today onwards is the part you can be accurate about, and it is the part that stops this happening again.