Hi maybe someone here can help - 

I tried to install Ubuntu on my desktop with a usb installer and got a black screen which I fixed by adding 'nomodeset' before quiet splash in the GRUB menu.

Now after installing I get the same black screen (with some noise) but I cannot enter the GRUB screen and use the same fix. On startup with F12 I get the dell bios screen and if I pick Ubunto it starts directly with no option to edit. 

I also tried using ctrl+alt+F* and nothing happened. 

Any idea how can this be fixed?

Thanks