This sounds like a front-end performance issue. Try clearing your cache and refreshing your screen to see if the data reappears.
If you deleted records from your previous find people search, you won't be able to re-import them to the same table - you'd need to reconfigure the people search from scratch.
If the issue persists after clearing cache, you can click on the source column in your People table to edit search parameters and re-run the import.