Where do you live? High heat is a sure cause of tomatoes failing to produce fruit. We can’t grow anything of quality here in most parts of Texas during the hottest months.
Western Iowa(Council Bluffs).
I’m in South Alabama, and I specifically grow ‘maters that are bred to put out fruit above 90 degrees and high humidity.
Try the following varieties:
Jeff Davis
Florida Pink
Atkinson
Tropic
Creole
Neptune
Sungold
You can google these varieties and find seeds at various places.