Sorry to hear that. I have the same machine and love it. I do still have days like that and can go sit down at it the very next day and absolutely sews perfect!
Do you have it on a frame?
Check the pressure adjustor and make sure it is in the N range.
Check the feed dogs and make sure they are dropped.
If this was in a bag recently, check the tension. Sometimes if I take mine somewhere, the tension gets bumped.
Make sure the bobbin thread went into the bobbin case the correct direction.
Lastly, read in the book about the threading. Sometimes it needs to go through two holes at the beginning, sometimes all three.