How to restore mdf file in sql server 2005?
You can use sp_attach_single_file_db or the newer version CREATE DATABASE database_name FOR ATTACH_REBUILD_LOG.  In both cases it will create a new log file for you.

Unfortunately because you have no log you will not be able to recover anything that has not been committed.  It is also a good idea to run a DBCC CHECKDB afterwards to make sure there is no other damage.