How do I rollback a dropped table using log?
Third party software are :

ApexSQL Log. It has free trial as well.

Toad for SQL Server - It has Log Reader management which Rolls back transactions in the transaction log without the need to restore from a backup

Native to SQL Server are below methods :

you can restore your Database from a backup, and then RESTORE Transaction LOGS to a point in time with the STOPAT = '6/10/2013 12:30AM' argument.

Read this excellent post from Paul Randall - Using fn_dblog, fn_dump_dblog, and restoring with STOPBEFOREMARK to an LSN