I have a laptop( sony vaio) with windows 10 and ubuntu. I had ubuntu12.x and I upgraded to ubuntu 14.04 (64 bit). My card is a nvidia geforce 540M. After the installation the laptop restarted and what I got was a black screen with a cursor blinking! I tried to use the recovery tools and I logged in as a root. I tried startx but I got error messages. No network access as well since I tried sudo apt-get update and I got again error messages. Any idea how to solve this problem?
George
assume: you have only one computer now you cannot update(you are sure the reason is network fail)
as all can work, you need graphical and network to get back
graphical problem may be caused by driver, so you can reboot your pc, press e to edit the boot option when display system choosing menu(if not display,try press shift when rebooting, then press e to edit the boot option); add nomodeset after option 'linux ...quite ...'(you can google nomodeset), this may workaround the driver problem
update problem, if it is really network problem as you said. the eaiest way to fix it is using twisted-wire; or you can try your phone with usb conneted to the pc as a wifi adaptor(it's easy for android)
PS: to check the network problem please do not use 'apt-get'
Finally, all above not working, try reinstall(keep /home partition not formatting), this is the final solution
