boot - Ubuntu seems locked

I'm using Ubuntu 14.04 with Windows 10 dual.

I don't know what happened, but when I tried to open ubuntu today, I only saw black screen. Then I shut the computer by force (pressing the power button) then reboot. After this moment, whenever I open Ubuntu:

• No tab on the left.


• No tab (including power) on the topright.


• No file, view etc. panel in any window.


• Alttab does not work.


• Ctrl alt t does not work.


• Alt f4 only works in closing browsers and other windows.


• Only Ctrl alt del works.

I don't want to format because I installed imporant python data and configurations which I don't want to go through again.