I have had to rebuild my web server & I use Plesk & restored all the data from external backup.
Got most things working apart from a problem with two site running Magento 1.9.1 which when I try to re-index via admin give me an error that it "Cannot initialize the indexer process".
I tried re-indexing vis ssh but got a warning that the base table
"catalog_product_website' doesn't exist, query was: SELECT `product_website"
didn't exist & sure enough in phpmyadmin there is no table in that name.
I have gone back to a database backup from July & that table doesn't exist but it does from a database from 2016 so I can only assume that at some point that table has been deprecated but for some reason it started looking for it again.