error after update (manual): Parse error: syntax error, unexpected end of file

I just wanted to update to the newest version (Sorry I don’t know the actual wp version) and it didn’t work automatically. Therefor I tried it manual by FTP.
Now the site doesn’t show anymore (!!) and this error occures:
Parse error: syntax error, unexpected end of file in /home/dastichtin/domains/stichtingdestad.com/public_html/wordpress/wp-includes/functions.php on line 5183

site:www.stichtingdestad.com

Unfortunately I logged out from the wp-admin and I cannot login anymore.
What to do??

First I tried to reload the complete back-up files via FTP but I still get the error.

I already checked the functions.php to see if some ending bracket was missing….I didn’t see anything strange, but it is very hard to check this immense file for me as a ‘dummy’. Could I try to replace the functions.php file by the wp-update version of functions.php that I downloaded yesterday (and which looks very different), or is that to tricky?

Please help!