1- How do I deal with this problem
One or more indexers are invalid. Make sure your Magento cron job is running.
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If for some reason you don't have access to command line (terminal) you can run reindex through Admin panel under
System->Index Management by selecting checkbox for the ones that say Reindex Required, from Actions dropdown select Update on Save and click Submit button.
Please note reindexing can take a while depending on how much data you have in your website so if you have alot of products then it's advisable to run one by one indexer.