Hello and sorry you're having problems. Offhand from what I've read if a manufacturer no longer supports Amazon- then an additional device such as a FireStick would be needed as a workaround. However it would not hurt to try the following since Vizio does not provide updates for these models any more- their new TV's and internet devices receive updates directly from a Wi Fi connection (no USB downloads are created any longer):
1. Turn the player off using the Power Button on the remote. Wait 15 seconds, then power the player.
2. Unplug the AC power cord for 15 seconds, then plug the power cord back into the outlet.
3. Go to the Settings Menu, select System. Scroll down to "Restore Factory Defaults".
With "Restore factory settings" highlighted, press OK.
4. Go to the Settings Menu, select System. Scroll down to "Restore Factory Defaults".
With "Restore factory settings and deactivate all connected applications" highlighted, press OK
This would cure any basic software glitches as being the cause of the problem, and you would then want to try to launch the Apps again. If Amazon is still not accessible- and since this player is quite old by today's standards, you would want to purchase a FireStick, or Fire Box at the link below and connect directly to your TV as a workaround:
If you need further assistance let me know. Please do not forget to click the 5 STAR RATING, at the top of the page for my efforts. It is my livelihood and you can follow up at any time if needed.