It is a bit frustrating that you wait for 2 months before any follow up on a reply to your OP to ask for
It looks you have been hacked by lack of security on your installation. You will probably get more help by reading READ__ME_TO_RECOVER_YOUR_DATA.
If you had important data and no recent backup, no one knows except the creator of the READ__ME_TO_RECOVER_YOUR_DATA. This is irresponsible to have important data and no recent backup. The solution is to secure your installation and define a backup strategy.
If you had important data and a recent backup, the obvious solution is to secure your installation and restore from your backup.
If you did not have important data, no harm has been done. But secure your installation and define a backup strategy.
The important things to remember are:
1- secure your installation
2- define a backup strategy