Problem Since yesterday. when I boot the computer, after the splash logo, the screen turns black. I can go to a tty screen, but anything that I try to open graphically fails. (I am not the most experienced terminal user.)
Last actions before the problem The only thing I can remember doing before this problem started is, installing extra TeX-live packages and updating the computer. I don't remember what it was that needed updating.
What I have done so far
(1) Gparted tells me one of my small partitions (~4 GB has a unknown file system). I haven't created such a small partition, and I am not sure from which other partition this has been 'taken'. I checked this post My computer boots to a black screen, what options do I have to fix it? and I looked at the answer about "if this occurred after an update", I will have a look at the boot partitioning issues. to see if I can find out more.
UPDATE: The 4GB partition apparently was my swap partition. I reformatted it to swap, the problem did not get fixed and this partition is back to being of a file system "unknown".
(2) Recovery mode doesn't 'open', i.e. on different options, partitions are checked and then nothing.
(3) Boot-repair didn't fix the problem (http://paste.ubuntu.com/6878058), but I reckon the boot is indeed not the problem.
(4) Other similar problems I found on forums were either with 12.04 upgrade to 12.10 (I have 13.10 64 bit), or it seems to have to do with their graphics cards. However I did not change anything about the graphics as far as I can remember for months.
My system I have Ubuntu 13.10 64 bit, single boot with several partitions, AMD64 Athlon II X3, 3.2 GHz, 4GB RAM, ATI Radeon HD4250.
What now? I will now keep on finding new things to try, but some of them are bit too complicated for me. If anyone can help me, you're help is very much appreciated.