Please help I can’t post anything to my blog

I’m in my admin area and I want to add a post or whatever to my blog.

For anything I write, it immediately gives me error messages in a red box, like:

Warning: Unexpected character in input: ”’ (ASCII=39) state=1 in /home/ethnicai/public_html/wp-admin/admin-ajax.php on line 88

Parse error: syntax error, unexpected $end in /home/ethnicai/public_html/wp-admin/admin-ajax.php on line 88

I’m only using simple words, no strange characters or anything.
It always gives me the same type of error message like above.

Any idea why it does that?