this morning i was using KDE plasma and i put the laptop on sleep mode then after that i tried to open the laptop and the system to complete my work but kde plasma not working then i reboot the laptop and in the login window i choose plasma to lagin in kde plasma environment but it dosen't working and i only saw a black screen then he took me again to login window

I had a similar problem when attempting to upgrade to Fedora 31. The /var partition was completely full. This was also prevent SDDM from working (sounds like you're using GDM). I was able to free it up by removing the massive log files in /var/log

I don't know if this helps, but it's worth a check.