system freezes

just want to add that i am not having nvidia
sudo lshw -C display
[sudo] password for ankit:
  *-display
       description: VGA compatible controller
       product: Sky Lake Integrated Graphics
       vendor: Intel Corporation
       physical id: 2
       bus info: pci@0000:00:02.0
       version: 07
       width: 64 bits
       clock: 33MHz
       capabilities: pciexpress msi pm vga_controller bus_master cap_list rom
       configuration: driver=i915 latency=0
       resources: irq:125 memory:b0000000-b0ffffff memory:a0000000-afffffff ioport:5000(size=64) memory:c0000-dffff

Is this the system with space problems in https://answers.launchpad.net/ubuntu/+question/688825 or a different one?

it is the same system with space problems . actually i was having installation problems and this 0 disk space error from a long time but my problem suddenly rise to new level when at one morning after entering the password , the system starts to hang although the mouse is working properly . i had to press the power button to turn off and then press again to start again but problem persists . i somehow manged to create a user from tty (ctrl+alt+f1) and from new user somehow got myself sudo rights . but i thinks i should ask an expert so that the same problem dont come in future . also i have some things in virtualbox of old sudo user which i want but due to this i am unable to do so . so thats why i ask . extremly sorry if that cause trouble .

Thanks Manfred Hampl, that solved my question.