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Ashik
Ashik, Mac Technician
Category: Mac
Satisfied Customers: 10342
Experience:  Bachelor of Computer Application (BCA), 9+ Years of Experience in troubleshooting Macs, iPhone, iPad, iPod etc
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Trying to restore an old computer to factory settings i get

Customer Question

trying to restore an old computer to factory settings i get to disk utility and 106.04 GB Toshiba Mk and under it is Jel.when i try to erase it says disk erase failed with the error "couldn't unmount disk"
Submitted: 1 year ago.
Category: Mac
Customer: replied 1 year ago.
I am trying to restore a macbook to factory setting. I get to Disk utility and try to erase and it won't do it. on the left side of the page is 160.04 GB TOSHIBA MK... UNDER IT IS JEL UNDER IT IN LIGHT GREY IS SUPER DRIVE THEN A LINE THEN DISK1
AND UNDER THAT MAC OS X Base System
Expert:  Ashik replied 1 year ago.
Hi and Welcome. My Name is ***** ***** I look forward to assisting you today with your question.
What version of Mac OS X are you using ?
Customer: replied 1 year ago.
10.7.5
Customer: replied 1 year ago.
it is not on this computer but another
Expert:  Ashik replied 1 year ago.
What version of Mac OS X are you using on the computer you trying to restore ?
Customer: replied 1 year ago.
whats the problem
Customer: replied 1 year ago.
10.7.5 is the OS X
Expert:  Ashik replied 1 year ago.
Did you try to erase it from the Disk Utility in Applications > Utilities folder or by booting into Mac OS X Utilities screen ?
Customer: replied 1 year ago.
booting in
Expert:  Ashik replied 1 year ago.
In Mac OS X Utilities screen, open Disk Utility. Then click on the first disk in the left column (the top one) and can you erase it ?
Customer: replied 1 year ago.
that is the one that starts with160.04. when i try to it says "disk erase failed Disk erase filed with the error:
Counted unmount disk
Expert:  Ashik replied 1 year ago.
How did you boot into OS X Utlities screen ? Using Command and R or using Option key ?
Customer: replied 1 year ago.
option
Expert:  Ashik replied 1 year ago.
Lets do it by booting into Internet recovery. Turn off your Mac. Then restart and immediately hold down Command and R keys at the same time for 10 seconds and this will boot into Mac OS X Utilities from internet. Then try to erase the hard drive (the main one or the sub one)
If that didn't work, then restart and hold down Command, Option and R keys for 10 seconds and this also boot into OS X Utilities screen. Can you erase from there ?
Please let know if that didn't work. There is another (indirect) way to completely erase everything and install a fresh OS X.
Only rate the answer after we've solved the problem.
Customer: replied 1 year ago.
didn't work
Expert:  Ashik replied 1 year ago.
Did you try to erase from both Command R and Command, Option R ?
Customer: replied 1 year ago.
i did Option first then according to your instructions I held down the Command and R and went from there
Customer: replied 1 year ago.
oh wait I didn't hold down option too
Customer: replied 1 year ago.
let me try again, sorry
Expert:  Ashik replied 1 year ago.
No, that won't work. Please follow my instructions exactly. Turn off your Mac. Then restart and immediately hold down Command and R keys at the same time for 10 seconds and this will boot into Mac OS X Utilities from internet. Then try to erase the hard drive (the main one or the sub one)
If that didn't work, then restart and hold down Command, Option and R keys for 10 seconds and this also boot into OS X Utilities screen. Can you erase from there ?
Don't hold down Option.
Customer: replied 1 year ago.
I did the command and R and that didn't work
Customer: replied 1 year ago.
so now should I hold down Command, option and R?
Expert:  Ashik replied 1 year ago.
Yes. Turn it off. Turn it on and immediately hold down Command, Option and R keys at the same for 20 seconds and does it boot into the Mac OS X Utilities screen ?
Customer: replied 1 year ago.
it boots into the screen I go to disk and it still won't let me
Expert:  Ashik replied 1 year ago.
How old is this Mac ?
Customer: replied 1 year ago.
2008????
Expert:  Ashik replied 1 year ago.
Do you have the discs came with it ?
Customer: replied 1 year ago.
no
Expert:  Ashik replied 1 year ago.
Do you have access to another Mac ?
Customer: replied 1 year ago.
I'm on it
Expert:  Ashik replied 1 year ago.
What version of Mac OS X are you using on it ?
Customer: replied 1 year ago.
yosemite 10. 10. 2
Expert:  Ashik replied 1 year ago.
And which Mac is this ? iMac, Macbook Pro etc
Customer: replied 1 year ago.
the one i am on is a macbook air
Expert:  Ashik replied 1 year ago.
What is the model of other Mac you are trying to restore ?
Customer: replied 1 year ago.
just a macbook
Expert:  Ashik replied 1 year ago.
Since the normal erase and install didn't work, I want you to do this please.Create a bootable Yosemite USB Disk from your Macbook Air, then boot to that drive on your Macbook. This will allow you to unmount the hard drive since you are running the utilities from USB drive.You can create bootable Yosmite drive using this utility --> http://diskmakerx.com/Follow the instructions in here to create the bootable drive --> http://blog.macsales.com/27530-create-a-bootable-yosemite-usb-install-drive-with-diskmaker-xAfter creating a bootable USB drive, connect it to your Macbook. Then restart your Macbook and immediately hold down Option key on your keyboard and this will boot into Startup manager screen. Select Yosemite USB drive and press return. This will boot into the Mac OS X Installation screen directly from the USB drive. Erase the internal hard disk again with Disk Utility. Then Reinstall Mac OS X.Please let me know how it goes. Only rate the answer after we solved the problem.