Application error - check your logs... error?? (NOT wordpress cache plugin)

I had built a small website with some basic php, and please be aware there is NO wordpress or plugins or anything involved.

It was working fine, i am a total beginner, but i had fixed all the bugs, it is just a basic set of pages with colour coded maps to hold some basic geographical data. So, we didn’t use it at the time (February or so this year), and 000webhost archived it. I have recently restored the website, however it no longer works, except for the pure html pages at the front. Whenever i click a link that leads to a php page, it says:

" Application error ## An error occurred in the website and your page could not be displayed. If you are the website owner, check your logs for details."

So, how do i check these logs or begin to troubleshoot this, please? As i say, all the other replies i’ve seen on this error message mentions the wp cache plugin, but I haven’t got anything like that.

Thanks in anticipation!