Tracking Unintended Row Changes
Brian,

Unfortunately the Windows event log and SQL log will not provide that information.

Fortunately there are several ways to audit a such activity. SQLShack has a good explanation on the various techniques and 3rd party tools

https://www.sqlshack.com/various-techniques-to-audit-sql-server-databases/

I had a similar situation at my work where I need to track some unintentional updates to a table that seemed to happen a couple of times a week. 

I decided to use out of the box SQL Server auditing features. I was able to track down who, where and when certain DML changes were occuring..

You need to first setup a server audit then create a database audit..

You can tailor your database audit to "update" statements on your specific table.. Limiting the audit to your table and "update" statements will limit the amount of auditing taking place.

https://docs.microsoft.com/en-us/sql/relational-databases/security/auditing/create-a-server-audit-and-database-audit-specification?view=sql-server-2017

You set up the server audit to log the activity to a file locally or somewhere on your network. Make sure the SQL Service account has write permissions to whatever location you choose. 

You will have to use the function sys.fn_get_audit_file to read the audit file. 

https://docs.microsoft.com/en-us/sql/relational-databases/system-functions/sys-fn-get-audit-file-transact-sql?view=sql-server-2017

After you have solved the issue you can simply disable or delete the server and database audit.