backup files confusion..

HI,

 we have no.of backup files like a,b,c,d.bak like that,

here problem is we are restoring c.bak file instead a.bak file, c.bak file restore that database now it's use how to resolve this problem with out drop the database.

HOW TO FIND THE WHICH "BACKUP FILE" ARE RESTORED WHY BECAUSE WE HAVE NO.OF BACKUP FILES THAT'S WHY I AM ASKING HOW TO FIND THE RESTORE BACKUP FILE.