Gmail notification on my Samsung Galaxy 3 The Gmail "envelope" notified me when and number of emails I had. Now I have to go in to Gmail to see if I have mail. How to fix?
The Gmail app icon doesn't display an unread messages count overlay (badge) in either stock Android or TouchWiz. So, either you have it confused with the stock email app (i.e. that's where you actually saw the unread message count on the envelope icon), or you're using a custom launcher (in which case, please specify which).

In any case, there are two ways I know of to get these icon overlay notifications.


Use a custom launcher. As implied above, there are third party launchers that can do this. Both Apex Launcher Pro and Nova Launcher Prime support unread message count overlays on the Gmail app. 

In Apex, you can change the badges' size, shape, and location (which corner of the icon), and you can even set the notification for one app to show up on the icon(s) for a different app. For example, I have my missed call count on a third party call log app's icon rather than the stock phone app icon, because that's where I usually want to look first when I have missed calls. If you really want to confuse yourself, you can have your Gmail unread count show up on the stock email icon, and your Exchange or POP3 account's unread count show up on the Gmail app. In other words, it's very flexible&mdash;any app's notification count can be placed on any other app's icons. The main limitation is that the count has a maximum of three digits. If you have 1000 or more unread, the badge shows 999+. But, if you have that many unread, it's questionable whether seeing the count is actually useful to you.

I don't know the details of what Nova is capable of, because I've only used the free version, in which the Unread Count feature is disabled.
Apps that add widgets with notification badges

Unread Badge for Gmail creates a widget that has an envelope icon with an overlay showing the Gmail unread count and opens the stock Gmail app if you tap it. This one can display larger numbers. I don't know what the limit is, but I can attest that it can show 5 digits. You have a selection of icons, but none of them look exactly like the Gmail icon (presumably because that's trademarked). You change the caption under the icon.

Notifyer Unread Count enables you to create widgets that look just like the app's own icon, with a notification count overlay badge. This one isn't specific to Gmail, it can be used for any app that reports notifications. 

Contrary to the app's name, however, it doesn't actually show you the unread count, it shows you the number of new messages since the last time you opened the app. However, depending on your needs, this can be an advantage. Even though I use Apex Launcher Pro, I use Notifyer for Gmail precisely for this reason. You can probably deduce from the fact that I can attest that the above app can show 5 figure counts that to me it's more useful to know how many new messages have come in than the total unread count. :)  

This app also lets you show counts from one app on another app's icon. In fact, it's even more flexible than Apex in that respect: you can show the counts from a given app on icons for multiple apps; you can set each Notifyer widget to show notifications from an app other than the one it opens (the icon is always from the app that the widget launches).

Another cool feature of this app is that you can set it to hide widgets that have a count of 0&mdash;when there are no new messages (or missed calls or whatever), the entire widget vanishes. Unfortunately, this appears to only be available as a global setting. Hopefully in a future version you'll be able to set this on a per-widget basis.