how to get his mane to grow back

My boy has about a 7" section of his mane completely rubbed off towards the base of his neck, and I don't know how to go about getting it to grow back. I think he is sticking his head through the rails to eat the grass on the other side, though I hardly ever see him doing it. It is now just skin in that section and looks really bad, but mostly im afraid of him rubbing the skin raw. Any suggestions on stopping this and getting the hair to grow back? I will be picking up some MTG, but I think if I put it on and he keeps rubbing it it will be all for not. I was thinking of putting a wrap around his neck but its more towards the base so I would think it would ride up, plus its either really hot or really wet so it would be uncomfortable I think. He always has good hay availible(not much fresh grass in his padock) so he doesnt NEED to poke his head through and I take him out to eat the ditches a few times a day. Again any suggestions would be great.

My suggestion would be to look into his skin condition. There is a plethora of things that could be causing this. It could be that flies and pests are bothering him, some sort of crud or bacteria, an allergic reaction, dry skin... etc etc. Does he show any signs of rubbing out the top of his tail? Does he ever have reactions to bug bites (swelling, obvious discomfort)?

If he's rubbed his mane completely off, I think it would have to be more intentional than just brushing against the fence trying to get grass. He may be itchy or uncomfortable in some way. My suggestion is to start of with getting his whole mane as clean as you can. Give him a bath and really work the shampoo into his mane for a few minutes, then rinse it off and keep rinsing until you're certain that there can't be any soap left.

Cowboy Magic sells a product called Krudbuster that may or may not help depending on the cause of his rubbing. I used it recently on my mare's tail because she was rubbing it out at the top and she does not appear to have rubbed it since. If it's just that he has dry itchy skin, you can supplement his feed with a cup of black oil sunflower seeds (the type that are sold for bird feeders) every day. The sunflower seeds usually improve skin and coat condition. You can read more about them here: Black Oil Sunflower Seeds for Horses

Finally, make sure he's thoroughly protected from pests with plenty of fly spray.

The MTG will probably help with growing back, but you're right... you need to resolve the cause before you can hope to recover from it. You can take a thorough approach and put all of my suggestions into effect immediately. Nothing will hurt him even if it isn't entirely necessary, and none of it is very costly. If he starts to improve then you're in luck! If he does not improve or worsens, call your vet and get a professional opinion on what is causing the problem.

How can I comb my horses mane without getting kicked?

I don't see how your horse can kick you when you're brushing its mane. Tail, maybe, but not mane...

That probably won't happen, at least not very easily

If you mean to say tail, then you can do this. Take the tail and hold to the side of your horse. Easy!

His skin looks and feels really heathly both where its rubbed of and where its not. He is pretty much a giraffe so when he does stick his head through the fence, its through the top rail. That spot is exactly where the fence hits. We do have unsanded rails that are pretty rough, so its probably accelerating the problem. I would really like to cover the area to see if it starts to grow back, but don't know how to go about doing that in the heat or rain.

As I said, I am not convinced that he's just happening to do this without doing so intentionally. Maybe you should try spying on him for a while. There was a horse at our barn that had allergies and was so itchy that he turned his head and neck to one side and rubbed it on the side of the barn and rubbed out the same general area. Try watching your horse to see if he really is reaching through the fence to graze or if he's using it to rub. If he is using it just to graze, it seems like the underside of his neck and chest might also be somewhat rubbed in the process. Have you checked that?

If you're going to try just covering his neck, you'll have to buy something that is meant for it, otherwise it might come off or he might get tangled in it. The neck covers are meant to be attached to blankets, so he'll have to be blanketed one way or another. Here's a few, but they're honestly more expensive than trying what I suggested. Particularly if you get different ones for different weather conditions. Such as mesh for hot weather and nylon with weatherproofing for rain.

TOUGH-1 Polar 600D Waterproof Poly Neck Cover Accessories Blankets and Sheets HorseLoverZ.com

TuffRider Fly Sheet With Neck Cover Fly Sheets Blankets and Sheets HorseLoverZ.com

Also keep in mind that if he's intentionally rubbing because it's itchy/uncomfortable and you make it so he can't but don't also treat the cause, he'll probably become even more uncomfortable.