This is a problem with the graphics driver and the BIOS.
1. The problem is caused by the computer selecting an external monitor (which may or may not be present) as the main monitor for the laptop. If you have an extra monitor, attach it to the Vostro and the screen will probably show up there.
2. Update the BIOS to A12. You can find the update on the Dell site. You might need to go looking for it specifically. When I used the Dell site to search for updates (of any kind), it led me to update the BIOS, but only to A09. I had to go back to the site and search for further BIOS updates in order to find A12.
3. You can try upgrading the graphics driver, but I don’t think that helped in my case. Disabling the graphics driver will force the screen back to the laptop monitor, but you will be using a very basic, generic graphics driver in that case, so you will have limited functionality. The above BIOS update is the only thing that worked for me.