Imac have black screen. Start Computer sound come on, no picture. The last time I used the computer I put it to sleep, it never came back. i tried everything that was suggested including puting in the start up disk. The disk would not eject. Some one

Question

Imac  have black screen. Start Computer sound come on, no picture. The last time I used the computer I put it to sleep, it never came back.  i tried everything that was suggested including puting in the start up disk.  The disk would not eject.  Some one suggested how to remove it and that did work.  Computer going to Apple hospital Tues. July 3,  thank you for all the suggestions.
Phyllis33

Answer 1

There is nothing wrong with the OS update.
Delete ALL your email accounts.
Restart Playbook
Put the accounts back and ensure they are all set with PUSH ON.  Manual (push off) will burn battery.
Similarly delete your wifi connections and add back when required. 
Turn off wifi is not connected to wifi. 
Any "hunting for connection" in email or wifi will burn up battery.