The .trn seems to be a SQL Server transactional log backup. I restored the .bak file only, but I dont see the data that I see on the production database. Is the reason related to the fact that I did not restore .trn file? If I need to restore .trn file now, how can I do that? Is this going to resolve the problem and the data will be similar to the production database?
yes, you must have take the backup of the log file as well then u will be able to restore the log file. At the time of backup u need to take backup of the both files backup and log then follow steps to restore database with log file.