Shell – Understanding sudoers:

Yeah - that is a "gotcha" for sure. Use visudo in the future to avoid that problem. I have a CentOS 7 VM, which is essentially the same as RHEL7; and I was able to use su - to become root without using sudo, because I know the root password. Do you know your password for the user, root?

In addition to the answers given in the comments, you should also note that your script will break on any filenames with spaces in them.

You can do all of this in a single command using find, rather than trying to parse a list of filenames output from find. Much more robust; handles filenames regardless of special characters or whitespace.

find "$1" -type f -exec chown "$2" {} \; -exec chmod 600 {} \;

Note that if the chown fails on a given file, the chmod will not be run on that file. That's probably the behavior you want anyway.

Since you already ran an erroneous command that removed execute permissions from your "Documents" directory, you need to add back execute permissions:

chmod u+x Documents

If there are more directories that erroneously had execute permissions removed, you should be able to fix them with:

find Documents -type d -exec chmod u+x {} \;

I don't think you'll need this, though, as once execute permissions were removed from "Documents" then none of its subdirectories would be accessible, so execute permissions wouldn't have been removed from them.