Undone in multiple ways: First and foremost (and quite possibly the issue that leads to the solution of everything else) is that Joomla (v. 3.9.1) is saying that I have 20 Extensions that need updating - 13 of these are directly associated with VirtueMart and the others are mostly language updates which I don't use anyhow.
The issue is, I show installed extension versions at 3.4.2 with 3.4.2 being the available update (see image that I will try to attach somewhere - I believe this is my first post).
Now I really wouldn't care that Joomla was telling me to install these 'already updated' updates if it were not for the fact that my carts are behaving badly. Drop down multiple product pricing isn't being calculated, cannot add multiples to cart with +/-, when typing in qty price doesn't change, adding to cart takes me to cart but it remains empty... clearly something is amiss.
So troubleshooting usually has me trying to re-install, but I'm pretty clueless and limited in my knowledge of Joomla / VirtueMart as the real admin left circa 2015 shortly after site first launched. I don't know how to approach a reinstall of VirtueMart or if it's even necessary given someone might recognize a fix. Also I don't know about the data - all the pricing info and descriptions that have been added over the years - whether its safe with a 'reinstall'.
Guidance would be greatly appreciated!
Usually I recommend updating on a working copy of Your site. Beginning with Joomla to 3.9.10. Do not uninstall VM, make a new install over the top of the current VM version. And do not do this on a live site.
Jörgen @ Kreativ Fotografi
Is there an example or tutorial somewhere/how to overwrite?? And what constitutes a non-live site? I'm truly a novice.
Please state from which version you updated to VM 3.4.2.
Mostly it is advisable to update the template and other plugins too before updating VirtueMart and as last step Joomla.
"Overwriting" means installing VirtueMart via the extension manager by uploading the installer zip or the single files included, even though the installation already exists. The process is similar to step 5 in the unofficial installation instruction here: https://www.virtuemart.in/getting-started/9-tutorial-installing-virtuemart
EDIT: For you it would mean, installing VM 3.4.2 over VM 3.4.2, sometimes this helps if the server had a timeout or something else went wrong.
In your case, I think, it will be the template or some other old extensions.
[edit, changed overriding to overwriting /JH]
EDIT: Thanks, JH, very true. ;-)
A live site is the site You are using for Your shop. A "non live site" is another copy of the site, either local or as a stagingcopy somewhere in your webspace. This does not risk Your live shop in case of a faulty update. When you see that Your copy is working as expected, update Your live site.
Please check Stefans link for updating instructions.
Jörgen @ Kreativ Fotografi
and just use akeeba for making a backup it is the most simple free software for that.