I have somehow messed up my permissions, switched the computer off to see if it helped, now can't start it at all. The startup bar stops a quarter of the way along. I've tried doing it in Safe mode as well. I' on an iMac running Yosemite.

On Saturday, August 20, 2016, Apple Support Communities Updates <

I Have managed to start up from my original installation disk, done a disk repair, but the 'info' says the permissions cannot be repaired. What are my options now?

TThank you again. sorry to be thick, but could you spell out exactly what I have to do there. So far I've been unable to boot my computer from anything other tha installation disk (snow leopard). I Used the disk utility to repair the disk, which it said was okay. Repair permissions was greyed out and I couldn't use it. The disk utility said disk permissions could not be repaired. I tried changing the startup disk before logging out so I could get access my files and copy them onto a stick or something, but the only options were the installation disk I had used to start up, and another icon with a question mark that I couldn't select anyway. So there is no option available yo start up except with a CD/DVD and I haven't got a more up to date one. I had previously tried all the start up key combinations that I had found online for this sort the situation, but nothing worked except a disk.

I'Ve now managed to start up in single user mode (thank you) and I can now see what you meant. The only trouble is I don't know how to navigate around all that text and what to actually do with it. My keyboard doesn't produce the expected results

Thanks again Eric, my computer is an iMac 10,1, late 2009, originally equipped with OS10.6.3, Snow leopard, now running (or not!) on Yosemite.

I have been concentrating today on getting another computer so I can get my work off to the printer tomorrow, but I'd dearly love to get back into the original if possible.

So if I get in in Single User mode, and wait for all the code to scroll out, I then type or paste diskutil repairPermissions / and hit return, is that right? (or does it need 'sudo' in there as well)

What will happen then, if it works? Will that fix it?

Once again, I do apologise for my ignorance

Ok thanks. I tried it and got this:

diskutil repairPermissions/

Unable to run because unable to use the DiskManagement framework.

Common reasons include, but are not limited to, the DiskArbitration framework being unavailable due to being booted in single-user mode

sudo diskutil repairPermissions/

sudo: unable to stat /etc/sudoers: Permission denied

sudo no valid shudders sources found, quitting

bash-3.2#

What I think I originally did was to set my permissions in the "everyone" section to 'read only', because I didn't understand what I was doing. At some point along the line, since being unable to start up, I managed to get the disk utility up and checked the disk, which it said was ok, but 'repair permissions' was greyed out, and I also saw a summary list of information that said something like "Permissions Repairable: No".

If I can't get back into the computer in the ordinary way I would like to know whether I can salvage my data, given that the disk is OK, and the data hasn't been disturbed while this is going on. If I get back in recovery mode and do 'Restore Mac OSX', would that leave my existing saved files untouched? Or would the permissions problem prevent that, too?

Once again, thank you so much, you've been brilliant