When you say
"access the host machine through the
VM. And vice-versa"
do you mean that you cannot access files (drag and drop into/out of the VM or do you mean network connectivity?
If you mean drag and drop out of/into VM check the following settings:
Under the options tab: shared folders. This will mount a shared folder on both machines, host and VM and allow you to have access to move files into and out of the VM.
If you mean network connectivity then make sure you have your VM tools installed. Installing the vm tools will also, usually, enable drag and drop functionality.