Files missing in library folders after LRc Update to V14.2 and V15

[AndyFisherPhotography]

Looking for help from the community. After I updated LRC to V14.2 from V14 I started to encounter issues with my LR Catalog where older folders wouldn't show any photos in the library module despite the folder name showing a items number next to it. 

Thought I left filters on and it wasn't that. 

Fast forward to yesterday - updated to V15.0 and all of the folders in the catlog show 0 images (see image below)
I have right clicked (windows user) to syncronise the folders and 90% have come back but LR encountered a problem in the process. 
I am still missing around 1000 photos from the folders but if you were to right click -> explorer and see the folder, the images are there. 

What can I do to get this fixed?

Not understanding how LR catalogs fully work technically, I tried creating a new catalog and import from the original folder thinking that there would be edit data saved to the files and well, I learnt quickly that this will not solve the problem as an alternative either. 

Tried on MAC too because all the files are stored on a DAS and that didn't help solve the matter either. 

[dj_paige]

It is likely LrC has upgraded the wrong catalog file. You need to find your previous catalog file, you can use your operating system's search feature to find all files on all disks that have a name ending with .LRCAT. Likely the largest such file is the one you want. Open each one by double-clicking on it in your operating system to see if it shows the photos you are expecting. (When you double-click to open in this case, LrC will want to upgrade each catalog in order to open it, this is expected here)