When I turn my apple on the grey apple comes up and the color helm and nil happends What do I do?

I use an Imac from some years spinal column like 3 years

When I turn my apple on the grey apple comes up and the color helm and nil happends What do I do?

try removing the battery-operated for a few seconds and reboot. If it still happen you might have to restore the operating system to the factory settings using the discs that come with your computer.
Start up the computer from the inventive MacOS X system disk. You insert it in the disk drive, hold down c and restart. After the computer starts up, travel to the utility folder which is in the applications folder. Run the disk utility program twice. Have it repair permissions, and repair tricky drive. Then try starting up from the regular hard drive. If it does, you've fixed it. If it doesn't, do a verbs install of your Mac Os X. It will save adjectives your old information, you won't lose anything. If it still won't start up, afterwards your hard drive is doomed to failure and need to be replaced.

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