Rethread machine and replace bobbin - then eat 2 no make that 3 pieces of chocolate.
If that doesn't work, unplug it than replug it in, just to let your machines know who the boss is
What are you taking for your cold? Breathing in steam (after making tea or cocoa) helps - break up the sinus pressure you get with a cold
Although I don't have a cold, I do have serious allergies -my DR has me taking - over the counter- SUPHEDRINE PE (generic for sudaped PE)- I take 3 in AM and 3 PM - really helps & non-drowsy
Hope you feel better soon.