The 340 driver is now considered unsupported and won't run on Ubuntu 21.04 with the current 5.11 kernel series it uses.
See : https://bugs.launchpad.net/ubuntu/+s...0/+bug/1916640
(The Ubuntu developers themselves have opted to stop patching it (as they patched it for kernels 5.5 to 5.9) and have scripted the package to just point to the open source the nouveau driver instead)
But luckily someone has created a ppa with the driver patched here: https://launchpad.net/~kelebek333/+a.../nvidia-legacy
Also, I don't think you ever installed the run file driver since the installation failed.
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