What kind of beads are they? Hobbycraft sell various kinds of thread wire or nylon. You will most likely need new fasterns as well. If you look on YouTube there are videos you could follow but it does depend on your beads as well. I've both made and mended lots of jewellery but it wouldn't be easy to describe to you what to do, a video is best. Elegran has given you a good answer too so you could go for that option. Good luck.