My Mouse Has Lost Hair Of Head And Does Not Eat What Should I Do?

It depends how old your mouse is, if its older than 3 years then im sorry to say it is likely that it is nearing the end of its life, :-(
whilst hair loss is quite cmmon and often not something to worry about, the lack of eating is likely to mean there is something else not right, small rodents are vulnerable to getting an illness called wet tail, it is like a stomach upset and can be caused by shock, i.e. If it has been droped or had a long traumatic move, also a change in food, dyes in knawing/bedding materials, or if the water has gone stagnant, see if its tail is, well, wet, and if it is get it to a vet soon. If caught early it is curable but not always, keep changing the food even if its not eating it, throw the food in the bowl out and refresh it every few days, try changing it to a different kind, it may just be fussy... Also you might want to try putting some rodent vitamines in its water, if it isnt eating then its quite likely to be drinking so its stomach feels fuller, you can get them in liquid form from most pet stores or vets, i got mine from pets at home, and you just need 2-3 drops in the water bottle. Hope this has helped and i hope your mouse gets better soon!