I am using Ubuntu 20.04LTS. When I upgraded my system from Ubuntu 18.xx/19.xx(sorry i don't remember) to Ubuntu 20.04, my screen lock suddenly stopped working.
Earlier when I press Windows(Super) + L, my Ubuntu screen locks and and require password to open but after upgrading it stopped working. And I even tried to lock from right corner from setting option to Lock, that is also not working.
I tried Super+Alt+L, this is also not working. If I do nothing for 15 min than laptop suspand but it does not ask for password when open. I saw my setting and everything was normal. See this picture
I looked on internet and tried every solution but It did not solve my problem. I tried these solution:
link1
Link2
Link3
Link4
update: I am using lightdm display manager so when in my terminal when I type dm-tool lock ,it lock the screen and require password to open.
I changed my display manager to gdm3 but that also didn't help.
Please help.
Thank You
