Do you see anything? Like a command prompt? If so, perhaps typing in the command "startx" would do something. If it boots into something that is totally black without even a command prompt, maybe try taking the second boot option underneath the default option when you're first booting in (this is known as "recovery mode"). See image below for an example of what I'm talking about. In this image the default option is "Ubuntu" and the second option is below it entitled "Advanced options for Ubuntu" -- your screen might show slightly different options. Regardless, take the second option below the first. This will give you a command prompt, which will give you an opportunity to try some things.
If "startx" does nothing, then perhaps the issue is a problem with the update to grub2 from grub ("grub" being the program that boots into Ubuntu -- it stands for "GNU GRand Unified Bootloader"). So, if you can get a command prompt (meaning, if there is some text such as user@yourcomputer:~$
after which you type in commands), then try the following command: "sudo update-grub". To summarize, here are the two commands I suggest trying first (if you can get a command prompt):
if that does nothing, then try this: