I was copying around 750GB of files into my external hard drive, estimated time was 10 hours. It significantly slowed down my laptop. I wanted to check what is inside rubbish bin so I opened it, but it was taking a long time to open. I had hundreds files in that bin, so it could take some time. I clicked the bin icon again, which probably caused another window to load. After an hour it still didn't open any rubbish bin window and my computer was frozen. I decided to restart the computer, so I held the power button to turn it off and then turn it on again.
Since then, from the moment it goes through boot process it ends at black screen. It doesn't load the desktop. I left the laptop overnight to see if it will respond after that long time, but it didn't. I tried restarting it couple of times, without result.
What are my options in this situation? I cannot reinstall the system since I have a disk full of data that I need to keep.
UPDATE:
I was doing recovery files using photorec and I selected wrong partitions. I noticed it after it had filled the whole space. I did that with all the partitions. And I guess no space on root partitions could cause this kind of problem.
I deleted all the folders with files that I recovered trough photorec. It freed 10 GB of space. Now there is a space, but still the problem occurs - black screen, it doesn't display desktop.
I updated the system, but it didn't help either. I'm thinking about boot files, maybe they are corrupted and hence it doesn't load the desktop.
UPDATE:
I tried:
sudo apt-get install --reinstall unity
and now Instead of just black screen I can see the Ubuntu logo with loading bar. But it still doesn't go to the desktop.