Blank page issue

First of all, I'm really sorry for an ignorant way of writing, but I don't know anything about websites, Joomla, Solidres and the company that did this for us is no longer offering any support.
We had the single subscription that expired the other day.
We're not quite sure since when (I'd say for a week or so), but the part of our website where Solidres is isn't working, it only shows a blank page. We had only a few reservations in the past 6 months and we don't really use that part of our website so that's why we're not 100% sure since when is it down.
Also, we're getting an error in Joomla that says SR_REINSTALL_USER_PLUGIN_IS_NEEDED and we're not sure if these two things are connected?
Every help is massively appreciated! Thank you!

Thank you!
The only problem is that I don't know how to do that :/ I know how to uninstall, I just don't know where to find the file to install it again? Will I lose my data after reinstalling? Sorry for the ignorance

Sadly I don't have the package downloaded as it was done by the company that built the site and they're not cooperative on this subject. I looked up the file manager on cpanel for plg_user_solidres (is this even the file I'm searching for?) and found these results:
/public_html/administrator/language/es-ES/es-ES.plg_user_solidres.sys.ini
/public_html/administrator/language/es-ES/es-ES.plg_user_solidres.ini
/public_html/administrator/language/en-GB/en-GB.plg_user_solidres.sys.ini
/public_html/administrator/language/en-GB/en-GB.plg_user_solidres.ini

I don't know if it's of any use to first download these files, delete them from the site and upload again or it's a silly idea?
When I unzip the Solidres file I download from the site, I don't know what is the file I need?