not sure what you are asking? the loss should be on the 2019 return if that is where it originated and then you should have a capital loss carryover for any amount brought forward. this will offset against any 2020 gains. 

Thank you very much. I did not do the client 2019, I am just about to do his 2020 tax return. So I am thinking his 2019 will need to be amended.

"So I am thinking his 2019 will need to be amended."

You are wanting to use the excess of the loss. Once any loss is applied to 2019, there might be carry over, or excess loss to use in 2020. Did they not enter the data properly for 2019? Did they not include the carry over info for your needs? What needs to be amended in 2019 for purposes of 2020?