|This is kind of a 'duh' tip, but the answer was nowhere to be found in my lengthy sewing machine manual, so I thought I'd post it in case anyone else runs across this problem.
If your fabric doesn't feed through your machine & you've tried starting & re-starting it & double checking every other obvious thing, make sure your feed dogs are up.
I almost never ever (as in maybe once a year at most) lower my feed dogs. And if you're like me & you don't always clean up after you've been sewing into the wee hours of the night, you might forget to raise your feed dogs back up. Then the next time you sew you might not remember that you ever lowered them in the first place & could spend an hour tearing out your hair.