Can we ask for prayers from Hazrat Mohammed (sallallahualaihiwasallam) while he is alive in his grave?

I have a query which i need to confirm from u..as per our belief hazrat mohammed (sallallahualaihiwasallam)is alive in his grave where he offers prayers and respond to salaam and durood send to him by any of the ummati..it was told to me at an early stage of my life that one can ask for prayers to a pious person who is alive,as he is much closer to allah in comparison to us..can we ask for prayers(dua)from fakhre alam(p.b.u.h) as he is alive in his grave,and allah never ignores him.plz throw some light on this matter.