El Capitan Update Troubles

[CopperHawk]

(First time posting on the forums, so really sorry if this is in the wrong area. )

So recently I attempted to updated to El Capitan from Snow Leopard. I had got it from the App Store, and moved on to actually installing it. However, the installation has failed about three times. It says it will take 24 minutes, but often takes an hour or more, then fails.

I'd like to either figure out why it isn't updating, and update it, or somehow cancel the update and return to the old OS. However, I have a few problems:
I didn't make a Time Machine backup. (I know, with 20/20 hindsight that was a mistake.)
Also, when I try to install, it says it failed because "a file is damaged" when I try to install it on Macintosh HD.

I've tried using Macintosh HD as a start up disk, and it says, "you can't change startup disk to selected disk could not gather enough information."

I've also tried restarting multiple times, with no success.

I tried doing system repair using utility functions, but I was told that after three attempts, a damaged file in Macintosh HD couldn't be repaired.


Anyway, I'm getting really desperate, and any help would be greatly appreciated. This is the only computer I have, so if you can help, you're a life saver.

Thanks.

 

[CopperHawk]

Help would be greatly appreciated. Sorry for the bump, just feeling pretty desperate.

 

[Cory Cooper]

Hello and welcome.

The installation failure could be caused by numerous things - corrupted El Capitan installer download, failing hardware components, Not enough free space on your hard drive, etc. This can be quite difficult to solve via the Internet, without being able to interact wth the Mac first-hand. If you had a current Time Machine or other backup, we could proceed with some troubleshooting steps. Since you do not, we would hate to suggest something that could cause you to lose any possibility of access you may have to your data.

Honestly, the best solution here is to have an Apple Store or Apple Authorized Service Provider take a look at it in person. Do you have any close to you?

C