I have previously used zorin OS and recently made a shift to tumbleweed. Everything is fine except that the screen resolution is only 1024768. I tried using even the xrandr command but it also shows only 1024768 resolution. The maximum display resolution my monitor supports is 1368*768 which I was getting on zorin OS. How can I get the same resolution in tumbleweed
Hi and welcome to the Forum 
Not booting this system (I suspect a laptop) with nomodeset by chance?
Can you show the output from;
cat /proc/cmdline
/sbin/lspci -nnk | egrep -A3 "VGA|Display|3D"
When all else fails - you can try to force the video mode (the VGA-0 might be something else xrandr will show you the correct name for your computer - in virtualbox guest it is virtual1)
the “cvt” command will give you the correct numbers to force into xrandr to make any resolution - just make sure the display can do what you force it to do.
llrainey@VM1:~> cvt 1368 768
# 1368x768 59.88 Hz (CVT) hsync: 47.79 kHz; pclk: 85.25 MHz
Modeline "1368x768_60.00" 85.25 1368 1440 1576 1784 768 771 781 798 -hsync +vsync
llrainey@VM1:~> cat forcevideo.sh
#!/usr/bin/bash
/usr/bin/xrandr --newmode "1368x768_60.00" 85.25 1368 1440 1576 1784 768 771 781 798 -hsync +vsync
/usr/bin/xrandr --addmode VGA-0 1368x768_60.00
/usr/bin/xrandr --output VGA-0 --mode 1368x768_60.00
llrainey@VM1:~>
then sh forcevideo.sh to change the resolution.