sewing machine help please!

[lispy]

Hi, I accidentally sewed over a zip and broke a needle which i replaced, now it sounds a bit louder (maybe my imagination) and the bottom thread isn't stitching properly - there's heaps of thread on the bottom of the fabric although from the top it looks fine... does this require professional help or is it easily fixed (have reloaded bobbin a million times). I didn't adjust any tension knobs...
Thanks for any advice.

You could try sewing on some scrap fabric to see if the machine sorts itself out. This has worked for me in the past.

Have a look at the bobbin area and check that there are no stray threads. Even the tiniest thread will do what you describe.

its a tension problem. need to work out if its bobbin or top tension that needs some adjusting and where you do this.

I teach textiles, and ime when this sort of thing happens (which is every day), sometimes just leaving it alone for a day or so sorts it out.

However, I have to say from my HUGE experience of jammed machines (every lesson, every day )it sounds like something has been damaged and may need repairing, as this should have been fine once the needle was replaced.