WampServer

I suggest you start again.

Uninstall WAMPServer, then reinstall whatever version of WAMPServer.

Now to get you old databases available ( you said you backed up all of the wamp folder)

Copy \oldwamp\bin\mysql\mysql{oldversion} to \wamp\bin\mysql\mysql{oldversion}

You will now have 2 versions of MYSQL installed in the new wampserver install.

So switch to the old version of MYSQL, Do a backup of all YOUR databases (not mysqls databases)

Switch to the new version of MYSQL and restore the data to the bnew release of MYSQL

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(Windows 10 Pro 64bit) (Wampserver 3.3.4 64bit) Aestan Tray Menu 3.2.5.4
<Apache versions MULTIPE> <PHP versions MULTIPLE> <MySQL Versions MULTIPLE>
<MariaDB versions MULTIPLE> <phpMyAdmin versions MULTIPLE> <MySQL Workbench 8.0.23>
Read The Manuals Apache -- MySQL -- PHP -- phpMyAdmin
Get your Apache/MySQL/mariaDB/PHP ADDONs here from the WAMPServer alternate Repo
-X-X-X- Backup your databases regularly Here is How dont regret it later! Yes even when developing -X-X-X-