not installing on Ubuntu

[BTA]

Installed Ubuntu 18.04 on a borrowed Lenovo 4446-25U. Installed urw_3.51_amd64.deb using Software Install & played for over an hour. Installed Clam TK Antivirus. URW disappeared. Could not reinstall. The URW3-Linux folder is still there with many files. Downloaded urw_3.51_amd64.deb, still could not reinstall.

What happened and how do I fix it?

[PALU]

Presumably the anti-virus SW didn't recognize UrW and butchered it. Trying to reinstall it will probably just cause the AV to repeat the process. To get UrW to work you probably will have to get the AV to recognize it as legitimate, but whether that is done by you through some settings or whether you'll have to go through some process to get the AV vendor to verify UrW is beyond me. I don't know about that AV and don't use Linux.
Removing the AV and reinstalling UrW will probably work, but I assume you actually wanted to have an AV program installed (although you might possibly try another one).

[BTA]

Sorry, forgot to mention, uninstalled Antivirus but still could not reinstall URW. Thinking about starting over with a fresh wipe and reinstall of Ubuntu Linux.

[koteko]

For a normal user, I believe it's counterproductive on Linux to install an antivirus (as shown in this case..). Just have a decent password and don't install stuff from dodgy websites, use the repositories instead

Clam antivirus is mostly used to scan Windows partitions for viruses, or in special cases. Luckily we have even less malware than MacOS around, and that's almost non-existent.

My suggestion: uninstall clam antivirus, uninstall urw, reboot and reinstall urw. Let me know the outcome, we'll take it from there.

[BTA]

yes. to all that, Koteko. In addition to that, with my reinstall, I encrypted the hard drive.

My passwords are strong. I write down whatever I am thinking at the time, like "Supercalifragilisticexpialidocious", turn the paper upside down and convert that into a password that looks something like what I wrote. S becomes 5, i becomes !, a becomes v, b becomes 9 or q. Great passwords, not my dog's name, the birthday of a close relative, nothing I would even remember! So, I have to put the passwords in my phone as a contact because, even I would never remember that.

[koteko]

Right, then forget about antivirus and enjoy the lighter Linux experience

If you have trouble with running urw on 18.04, you might need my modified package, see here:

https://www.unrealworld.fi/forums/index.php?topic=1981.msg5943#msg5943