I have installed paraview 3.8 on a computer. As you can see in  when I open the program, the window looks normal. However, when I open examples/can.ex2 and then select all variables and click on apply, the window becomes ugly .
What can be the issue then? I have installed that on Windows 10.
Welcome Mahmood to the ParaView community!
You downloaded ParaView 5.8, not 3.8.
You are very likely seeing the Intel driver bug. https://gitlab.kitware.com/paraview/paraview/issues/19364.
Thank you very much. Seems to be a popular problem. On my Asus UX310, the installed version of Intel HD display driver 620 is 18.104.22.16862 while the last uploaded version on asus site is 22.214.171.12486 (older versions are available for download). I guess the driver has been updated by microsoft update.
Nonetheless, when I switched to the Nvidia device, the problem got solved and I am now able to continue the tutorials.