Well, registration of Willis not necessary to give effect of the Will. rather you require to get Probate of the Will which takes time.
Even if we consider that there is no Will then also you have sahre in the land along with your brother , other siblings and mother ,if alive.
So in other words your brother can not sell the whole land.
In that context you can file suit for declaration to nullify the sale made by your brother and claim your due share.