USB ports don't work

I installed a VM vSphere on a SERVER (vsphere Hypervisor 6.5 - ESEXi).

At first the server recognize the USBs keyboard and mouse. And I was able to configure it (most of all the network configuration of the server, not much more). But after configuring some virtual machines, and after installing the vCenter, the server turn off the USB.

Now, I can’t use the keyboard and mouse on the server itself. When the SERVER is booting, the Keyboard and mouse seem to work fine. But then, it seems that power off the USB ports. For this reason, my virtual machines can’t see the USB either.

How can I enable them again? HOw can I solve this issue?

The server is a: LENOVO x3550 Server 32 Gb RAM, 2x1TB HD.

Thanks.

Dynamium