How to get the random administrator password again

I have a problem, and it is that some time ago I installed OpenVas, and when it was completely configured the computer turned off.
The next time I turned it on, the random password no longer appeared.
And tried to uninstall and reinstall it. Nothing works.
I hope you can help me.
Thanks in advance!!

Please check the category for your post, it seems you use a uncoordinated integration, please contact your 3rd party packet vendor for help on removing configurations left over from your packet vendor.