How to edit smart object text in photoshop?

If the text was converted to a Smart Object, you can't just click and type to edit it like a normal text layer. Here's what you do:

1. Double-click on the Smart Object's thumbnail in the Layers panel. This will open the Smart Object as a separate .psb file.
2. In this new document, you should see your original text layer (if it was still editable when it was made into a Smart Object) or a rasterized layer. If it's a text layer, just use the Type Tool (T) to edit the text. If it's rasterized, you'll have to repaint or recreate it, which is a hassle.
3. Once you've made your changes, Save the .psb file (File > Save or Ctrl+S). Then close it.
4. Go back to your main Photoshop document. The text should now be updated!

This is the power of Smart Objects—non-destructive editing! Always try to keep layers as Smart Objects when you think you might need to change them later.