Parse Error - Unable to load content

Hi

Getting an error when trying to create an event...popup appears with the message 'Parse error. unable to load content'

Searched forums and the only related thing that I found regarded having an index.html ....but I haven't got that!
It's funny as it's been working fine for ages!

however, a few days ago my site suddenly went blank, with and php error showing an error on line 10 of the file libraries/vendor/joomla/utilities/src/ArrayHelper.php

I ended up commenting out the top line just to get the site to work..so I assume that it might be something to do with this....maybe!

The only thing that I added on Wednesday was an Instgram module on the news page....but disabling this didn't make any difference.

Thanks
Paul