What Do I Do if the Canning Lids Did Not Seal?

First of all, was this a "process for 10 minutes", then pull out of the boiling water and set in a non-drafty place to let seal, or was it a "pour boiling jam into clean jars, put fresh rubber rimmed sealing lids on, and screw metal lids down (snug, but not as tight as some think is necessary), then turn upside down for a few minutes, (I usually pour each jar full, do the process, then start turning them back over, in the same order I turned them upside down to start with)? After either one has had time to seal, and if you gently press and the top does not seal, you can slowly reheat, jar and all, after replacing the sealing flat part, and making sure the top of the jar is clean and no jam is stuck, which might have prevented sealing in the first place, and retry the 10 minute bath, or the "turn upside down". In my 50 plus years of canning, I have redone many jars of jam, jelly, homemade fruit pancake syrup, and such, with maybe a total of 2 or 3 that eventually developed a bit of mold, after months in storage. Even that, if there isn't much, can be spooned out, and the inside of the jar wiped with a damp paper towel. Don't waste anything if you don't have to.

I'm new to canning but did you make sure to remove the air bubbles and wipe the rim and threads dry before you put the lid on? That might help on the next batch.