On SHIELD, an installed player can be reached through the full Apps view even when it is absent from the favourite row. Use that route before concluding that the application has been deleted.
NVIDIA documents a long press of Home as a shortcut to Apps on the supported SHIELD interface. Keep that action distinct from remote shortcuts described for another Android TV device.

Open the complete application view
From the SHIELD home screen, select Apps or use the documented Home long press. Look for the intended player by its exact name and icon. If the home row contains only a few favourites, the full list is the better place to check installation.
A regular press and a long press can have different effects. Hold deliberately until the intended view appears, then release. If your remote or customized setup behaves differently, use the visible Apps icon instead of repeatedly pressing buttons without a known result.
Launch before making changes
Select the player once to open it. If it opens normally, the missing favourite is a launcher issue rather than an absent application. Return to Apps and use the tile’s long-press Select menu to inspect supported move or favourite actions.
Read the command before confirming. The same management menu can offer Uninstall, which is a different and more consequential task. There is no reason to remove and restore a functioning application just to make it easier to reach.
If the player is absent from Apps, search the genuine Google Play listing. Read whether the store offers Open or Install and verify the developer before any redownload. An unfamiliar app with a similar name should not replace the original by accident.
Useful answers
Does long-pressing Home work on every Android TV remote?
Do not assume so. This shortcut is documented for the SHIELD interface; other devices can assign different actions.
Should I reinstall to restore a favourite icon?
First check Apps and the supported favourite or move menu. A working installation usually does not need removal for launcher organization.