Step 1: Backup the current database transaction log
BACKUP LOG [@DBName] TO DISK='[Target physical path]' WITH FORMAT, NO_TRUNCATE
Step 2: Restore the database using a database backup file. (The create date of the backup file must ahead of the date when you want to recover to)
RESTORE DATABASE [@DBName] FROM DISK='[Complete database backup file physical path]' WITH NORECOVERY
Step 3: Restore to the log point
RESTORE LOG [@DBName] FROM DISK='[Log backup file physical path]' WITH RECOVERY , STOPAT='02/01/2009 00:00'