Help undoing an accidental restore on SQL Server 2014
First off...   I think it is best to come clean to your manager on such issues.  The business will notice the missing data and he will not appreciate being blindsided and not having all the facts at hand.  In that event,  things will be even worse for you.  If you have no formal background in DBAing, you have no business doing DBA tasks and/or the real production DBAs ( if they even exist ) should have ensured that the business is protected against such human errors.

Simply put there is no way to restore individual rows auto-magically. There are tool set available ( Red Gate Data Compare springs to mind ) that allow you to compare data sets and build scripts of the differences, but it is upto you to decide which changes are good.