Hello guys … I ran update yesterday then after reboot i stuck at blinking cursor during boot. I temporarily fixed it by uninstalling nvidia driver “sudo pacman -R nvidia-340xx”
But I need nvidia driver. how can i fix the boot stuck without removing nvidia driver…
There are a few potential things to look at. First, the Arch wiki page:
https://wiki.archlinux.org/index.php/NVIDIA
Second, the nvidia-installer package (or nvidia-installer-dkms) should be able to install and configure the correct driver for you.
Third, nvidia-340xx is an AUR package so might end up breaking when repo packages are updated. You might need to to wait until the package is updated (e.g. for kernel 5.8).
Welcome!
Welcome! 
Could you show the output of
lspci -vnn | grep -P 'VGA|Display'
This is to check if your card is still properly supported…