Had Ubuntu installed and realized that I don't know root password
I used to be a Linux developer, but I have not used Linux or anything UNIX-like for a long time (more than 10 years). I had it installed by someone else and assumed that the root password is not set. Turned out - it has been. I can logged in as "owner" because I have guessed the password ("password") but no such luck with root. Can anything (other than reinstallation) be done? Is there some default password that root gets at installation that someone at this forum knows? Any other suggestions?
Thank you in advance.