More info required at a minimum:
Host OS and version
Guest OS and version
Version of Workstation
Make sure that the guest OS and bitness selected for the VM matches the actual guest OS installed within the VM.
Hope this helps,
Wil| Author of Vimalin. The virtual machine Backup app for VMware Desktop Products
| Vimalin : Automated backups for VMware Fusion and VMware Workstation and Player
| More info at https://www.vimalin.com
| Twitter @wilva
| VMware Wiki at http://www.vi-toolkit.com
Add a virtual DVD/CDROM drive to the configuration of the VM (even if you have one). It does not even need to be in the "Connected" state at the VM and it does not need to have an ISO file.
I found that without a virtual DVD/CDROM drive as part of the virtual hardware configuration of the VM, the "Install/Reinstall VMware Tools" get disabled/greyed out (in both Fusion and Workstation Pro).