"looked in the moodledata but all the folders and cache is empty"
All the folders? including lang?
You don't have cli and hosting provider won't do any cli scripts for you.
You attempted upgrade and discovered after the attempt that 3.11 required a 5.7 of MySQL and your shared hosting package only offered 5.6.
So the environment check moodle does upon upgrades, alerted you to that fact and stopped - or do you re-call if it started to update tables? (it shouldn't have done that)
You then had to put back the old moodle code ... all of it ... and remove the 3.11 code. How did you do that? Did you use a cPanel site restore?
May I ask if you used a thing called Softaculous to upgrade? (it is related)
Am guessing your shared hosting uses cPanel. If it does, is there a 'Terminal' icon in cPanel?
Well, you could try this:
go directly to https://yoursite/admin/purgecaches.php
that's an auto ... no prompts no ability to select what caches ... supposed to just do it.
As far as your comment on WordPress and Joomla ... just about all hosting provides offer those two. And neither of those two are a learning management system (LMS). Between the 3, Moodle is and always has been an application that required more resources as one upgraded and was more sensitive to versions of software (php/mysql) needed to run it. So one cannot compare the three farily!
And now my comment: this just keeps getting worse. You've not resolved your messages issue and now more issues. You keep seeing folks in forums recommending command line scripts but your shared hosting doesn't allow you to use command line scripts and hosting provider won't run them for you.
I've asked but you've not responded ... does your hosting provider offer a 'higher' (allows user to do more) shared hosting plan? One that has a 'Terminal' icon in cPanel?
Care to share where you are hosting? What provider?
Also, check your PM here on moodle.org. Please respond there.
'SoS', Ken