fresthetic

this might be a silly question but how do I download the file? Or should I just copy and paste in a text file and save as admin-ajax.php?

Also, should I install it anywhere specific?

How would I get an detailed explanation of the 500 error? It seems to pop up whenever I try to login to wordpress. Is there another way to see the error log?

The error reads:

This page isn’t working
fresthetic.com is currently unable to handle this request.
HTTP ERROR 500

Not sure what required file is missing. Nothing was moved or replaced. This just happened all of a sudden. Its been a while since we updated the site. Possibly a year.

Not sure what happened to the css file either or the SSL. I don’t actually know how to install an SSL. I honestly thought woocommerce would automatically install something like that.

Does the entire wordpress plugin have to be reinstalled? Would I lose all my sites information? Or, can I get any of the files listed above and replace them individually to make the site work again?