If someone is comatose, on life support and has no brain waves can they?

Question

If someone is comatose, on life support and has no brain waves can they ever come back?

Answer 1

thats what happened to my gran, she rapidly lost her  ability to move then speak, thenthink, then her brain died. it happened in about 3 weeks, from being perfectly fit and healthy. the doctors did a post mortem and still dont know why

Answer 2

just a miracle, some patient gets back, but when brain is involve is not probably.

Answer 3

coma yes, life support maybe but rare, no brain waves no, they are basically dead.  

Answer 4

No if there is no brain waves. The brain runs all the systems in the body for example heart it tell when to  beat or the lungs  it tells them when to take a breath or exhale. It does it all  and with it out it no life. You can be put on machines to support life but thats not living.