Mac have trouble starting up.

Question

Hello!
For some reason, my mac have trouble starting up. I've tried using the apple guide about how to fix the issue/ perform a safe booth but it doesn't work.
SYMPTOMS:
1. when turned on: the screen displays an apple screen with a loading continueous circle and stays there FOREVER.
after turning on and off for several times, it finally works. However, most of the time when it works/actually starts up, it cannot be connected the internet.
2. The mac also have trouble with the itune as I cannot sync any device to it and froze.
3.  I cannot update my mac. It suggested that in order to update, the mac must be restart so the installation can take place but when its starting
installing the update, the message then appear and says " an error occured durin installation" then it restarts and the process of trouble starting up repeats (back to 1.).
** Incidence before this happens**
A few days before it happened, there was a power shut down at my house, thus the mac was turned off incorrectly. so I have to turn on the mac again before it was turned off again by the power shut down.  IT HAPPENED 3 TIMEs
Since then the Mac was slow and starting to become less responsive. Then the trouble starting up occurs.
PLEASE HELP!!!!!!!
Thank you very much

Answer 1

hi,
I booted the computer and insert the disc then press c. but nothing happens. Infact the imac wont eject the disc when I press the eject button.
What should I do?
Thank you!!!!!!!