What does your Layers panel look like?
Assuming the layers on which you added text are still Text layers, and haven't been rasterized, what error or failure are you observing when you click the T tool on the text?
When I clicked the T tool on text, there is no response, the text act as if it is part of the image.
I created 3 layers of text, since I needed to add quite some text in different locations. I didn't flatten or merge them, and just saved as a .psd file. Come to think of it, it popped up some kind of question like maximum compatibility, and I clicked ok without thinking. Did I rasterize the text?
No, the Maximum Compatability setting won't cause text rasterization.
Is the layer with the text on it selected in your Layers panel when you're trying to click on the text to edit it?
If possible, could you capture your screen right at the time before you would like to click to edit text, save it as a JPEG, and post it here with the little "camera" icon? Often times if something is amiss people can spot it by looking at a screenshot.