Restore the sql server 2014 database on specific time

Good day sirs, we encountered a problem in our database (lets call db1) and I hope you can help me with it 🙁

Last August 19, we generate a backup file but on Aug. 20 we fail do so. August 24 my co-worker update the database db1 and restore a .bak file to it.

Now the problem is the original records are now gone and we have to get all the records on Aug. 20 but we do not have a .bak file for that specific time. Is there a way to rollback the action done last aug. 24?