Level 1

How to record the pay back of a loan if the loan was not recorded in the beginning?

I joined this company in June 2018. The record of this company before June was not clear and many records are missing. Today, my boss said that we have to pay back a loan we had made in Jan 2018. (Let's say the loan = USD10,000). However, when I check the record of Jan 2018, there was no record of USD10,000 had been received... For I loan that I have never borrowed but I have to pay back now, how can I record this? Just treat this USD10,000 as an expense of this month?