not any film in paticular and you can all have a good laugh at me if you want but I would certainly say a Doris Day, film makes you feel good when your feeling a bit down in the dumps.
For me it has to be 'Tammy' with Debbie ReynolRAB and Leslie Nielson or 'The Long Grey Line' with Tyrone Power and Maureen O'Hara (a real tear jerker).
Both quite old films but worth watching - IMO anyway.