@ Lizzy274… What I do with mine, if they need fixing is to fill the groove with "J.B.Weld",it is a two part epoxy, very strong and hard, which is available in any hardware or auto parts store. I can't find your profile so i'm not sure of your age or your capabilities to do this. I'm sure you can do this by yourself though. Mix the two part's of the JB Weld together in equal parts from each tube. Apply just a small amount into the old string groove, a groove that tiny you can use a toothpick to apply the mixture, let it harden thoroughly, read the back of the package for drying time, you can sand it smooth using a very fine finger nail file or fine sandpaper, I think the nail file would work the best, it's more controlable than sandpaper, be very carefull not to apply too much, otherwise you'll have it all over the place. I apply a strip of masking tape on the fingerboard, tight to the nut, that keeps the epoxy from getting on the fingerboard. After sanding, use a very small three corneded / triangle file to regroove it, being carefull this time not to go to deep. The E string should be fllush or just a bit above the nut, you will be able to feel the top of the string when you rub your finger across it. Apply masking tape on both side's of the nut, you don't need to get any on the wood finish. There is not a cleaner that will remove the JB without damaging the finish, so be EXTRA carefull.

The J.B.Weld is black in color so it will match the nut, unless the nut on your violin is white.

Good luck, I hope this help's. Will save you money not having to take it in to a Luthier.

                              You can do it.

 Ok, Lizzy,,, I just found out your age is 13,, ask your Dad or another male person to help you. Older brother ?

Again I stand corrected.