Directory lookup for the file "C:\CodePlex Database\AdventureWorks2012_log.ldf" failed with the operating system error 2(The system cannot find the file specified.). (Microsoft SQL Server, Error: 5133)
SQL server can't find the log file. Have you double checked that it's in the path mentioned above?
If you're restoring from the GUI you can change the path to the log file in the bottom half of the attach dialogue. or just change the path in your create database statement.
CREATE DATABASE AdventureWorks2012 ON (FILENAME = 'M:\Data\AdventureWorks2012_Data.mdf'),
(FILENAME = 'L:\Tlogs\AdventureWorks2012_Log.ldf') FOR ATTACH;