Lost files since renamed folder

I had installed a virtual machine in mnt/Linux-VM

This folder was supposed to be mounted on a separate partition and mistakenly I assumed so – but it was not since I have made a mistake in etc/fstab.
So the VM of min. 3GB was on the system partition.

Since I had a parse error in fstab (could see this while booting – antiX Linux) I renamed that folder to LnxVM (I didn’t know the error, assumed it migh).
fstab is now correct, the partition is mounted to /mnt/LnxVM

But since the folder in which the VM files had been installed doesn’t exist anymore, the 3GB VM file is not displayed anymore…
nowhere, have seeked trash files, on the system partition but nothing.

But the 3GB are still used on the system partition as it is allmost full. Before there where around 4GB free space…
How can I find and delete the lost files (virtualbox .vmdk & .vbox) ??

Thanks for every tip.