After replacing the bobbin the sewing hook/bobbin doesnt turn anymore. It will spin if you turn the wheel backwards but it wont do anything when turned forward.

Try to turn the hand wheel backwards possible thread stuck on the needle hook by the bobbin. Take the bobbin out and remove the face plate and clean machine.

If handwheel does not turn, you may have thread jammed in the hook. First try to force the handwheel BACKWARDS to try to force thread back out of hook. If handwheel turns, look around hook area and you will probably see a small piece of thread. Remove it with tweezers. To help eliminate this from happening, be sure to hold the needle thread when starting off.

Bobbin won't spin in hook? .. you may have something blocking the thread 'path'...or sensors? Try threading manually, right through with some unwaxed floss... while the machine is turned off.. or better still.. as you do each thread 'tension' area... check with a flashlight to see there isn't anything lodged (old threads caught anywhere...) when was the last time you had your machine cleaned?

possibly needs new belt or belt adjustment.

Never EVER turn your wheel backwards... that causes it to go out of time. Take your machine in for Timing.

it's possible that either a part is worn, broken, or damaged only a sewing machine repair shop can tell what's wrong

Probably something jammed in or near the bobbin case or hook area.

Thread is caught in the hook...Remove the upper thread and bobbin case...turn the hand wheel backwards and forwards by hand and remove the thread remands. Good Luck

You need to remove bobbin case and turn hand wheel backwards and forwards by hand till needle comes up and remove race hook cover and hook....remove all thread remands.. and reassemble.