Don't let a broken clasp stop you from wearing your favourite necklace. Use a paper clip to make your necklace wearable again until you get a replacement clasp.
Slide the paper clip through the ring that connects the clasp to the chain. Keep going until the ring sits in the middle of the paperclip. Then, whenever you want to wear the necklace, slide the other side of the clasp (the loop part) onto the paper clip and stop when it gets to the first curve.
This should hold your necklace together until you get a chance to replace the broken clasp with one from your local jewellery or craft store. If you don't have the pliers to switch out the clasp yourself, most jewellery store employees will be happy to do it for you (especially if you bought the clasp from them).
DIY: "Fixing Things Because You're Broke" [Buttoned Bears]