Was using 'The Events Calendar' plugin on a website, plugin seemed to randomly delete itself and a php error message was shown.

Now when I try to re-install the plugin I'm getting an 'update failed' error message and the following text:

"Installation failed: 504 Gateway Time-out 504 Gateway Time-out nginx/1.15.8 "

When I go into FTP, the plugin folder still exists within the back-end. I've spent ages adding events onto the calendar before it broke.

How can I resolve this issue? Worried about deleting the folder as I don't want to lose the event data.

My site is www.wheatfen and webhost is Fasthosts (DO NOT use them as they are shocking).

Thanks.