Deleted footer.php code

Hi,
I have accidently managed to delete my entire footer.php code for Sydney 1.53 theme! ?? Now my website does not work, will not load. I have tried copying and pasting a footer.php code from another forum of someone who did the same thing but this also will not work for me when I hit ‘update’ the message comes up ‘Unable to communicate back with site to check for fatal errors, so the PHP change was reverted. You will need to upload your PHP file change by some other means, such as by using SFTP’ and I have no idea what this means.

Your help would be hugely appreciated.

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