Hairline waxed and now I hate it - will it grow back again because I want them back?

Some hairs may grow back and some hairs likely will not. You'll need to wait 6 months to see where things end up.  It is unlikely that all the hairs will return but a good proportion likely will depending on your current age and whether you had any underlying hair loss conditions or not. 

If you lose hair, and want them back, transplantation can be an option for forehead reduction and correcting  asymmetry on your frontal hair line/forelock.I advice you have a FUE; you would get the desired hairline in just one sesssion of dense packing hair transplant. 

If you waxed your hairline to pull out the hairs, it may not come back. You will know in about 6 months when the hair recycles