Cindy, try this and see if it helps.
Reset your machine; totally turn it off and then turn it on and set the stiches all over again.
check the tension
use a NEW needle
check the thread to make sure it isn't catching on something at the top of the machine. maybe the thread thingy to keep a spool on is not allowing the spool to rotate.
rethread your machine. maybe the thread wrapped around the part that goes up and down
Rewind a new bobbin. If it loaded uneveningly it will not work right.
is your feeddog up?
is there something wrong with your stitch in the ditch foot? sometimes they get stuck and won't stitch right. mine needs to be messed with a little then its ok.
Somewhere along the line it will go back to working again. If your machine hasn't been serviced in a year or so, it may be time to get that done too. Alignment is a must. But check all of the above before running out for service.
Maybe now is a good time for a quick swig before going back to your machine. And it wouldn't hurt to tell your girl how much you love and need her right now. And that she's a wonderful friend to you. bla bla bla. Go heavy on that. LOL
I hope you get back on track real soon. Let us know what makes it all better.