PLEASE HELP I may have ruined my whole system

[jack17]

Okay I will start from the beginning. I needed to gain access to my /usr/ folder so I ran the command

sudo chmod 600 /usr/

This is where everything messed up. I now cannot run any programs because I get an error saying

"Failed to execute child process "exo-open" (Permission denied)""

[Crusty Old Fart]

Maybe putting the permission settings back to what they were originally would fix the problem.
On my system, /usr looks like this:

drwxr-xr-x  10 root root  4096 2011-02-04 19:26 usr

So, that would be:

sudo chmod 755 usr

I hope the solution is that simple.

[jack17]

I am now unable to boot Ubuntu. Plus when I was booted into it I couldn't even open terminal it would return the "Failed to execute child process "exo-open" (Permission denied)"" error

[Petro Dawg]

You may need to live boot using a DVD/USB, mount the hard-drive, and fix the permissions from there.

[jack17]

How would I go about doing this? I am a newbie

[Crusty Old Fart]

There's something else I didn't notice earlier.
You wrote that you used the command:

sudo chmod 600 /usr/

When I ran a similar command on my system, on a directory I named: x, I got an error:

chmod 600 /x/

~~~ Output ~~~

chmod: cannot access `/x/': No such file or directory

I'm surprised the command you entered did anything at all.
So I have no idea what happened to your system when you tried to chmod on /usr/ instead of usr without being embedded in slashes.

How would I go about doing this? I am a newbie

Did you install Ubuntu using a CD/DVD disk, or did you use a thumb drive?