Yes, it sounds like it is a timing issue. The needle is not picking up the bobbin thread. My little embroidery machine did the same last wk --I found instructions on line and repaired myself. It entails getting access to the timing belt and re-setting the needle. If you are not daring, you might prefer taking it for repair. I diagnosed your problem assuming you did not change needle between "yesterday" and the next day when problems arose. Or that you have not loaded your bobbin backwards. I hope it was one of the two above....good luck.

Is your bobbin out of thread?

Is the bobbin inserted correctly?

Is the bobbin case threaded correctly?

Is the bobbin case inserted correctly?

Is the flat side if the needle facing in the correct direction?

Does the needle need to be changed? Other than that, I'd guess timing issue as well.