Sounds like you’re using VMware Workstation? Is it the Player or Pro version?
Thanks for posting in VMware communities.
What is the OS which you are trying to install ?
If this is an already installed OS and if you are unable to boot, check if the VM was created with BIOS or UEFI.
The VM was installed with UEFI.
The boot setting is changed to BIOS, the bootloader of the OS will still be configured for UEFI
The OS will not boot, you will get message "operating system not found".
vSphere Install-Upgrade SupportVMware Install/Upgrade Team