if you have a nvidia graphic card try this;
#commands to fix suspending computer
sudo micro /etc/modprobe.d/nvidia-preserve-video-memory.conf
#paste the line below
options nvidia NVreg_PreserveVideoMemoryAllocations=1
#press Ctrl s and then Ctrl q to save file
#activate services.
sudo systemctl enable nvidia-suspend.service
sudo systemctl enable nvidia-hibernate.service
sudo systemctl enable nvidia-resume.service
#reboot.