When i tried using the type tool, the font was very very very tiny (almost unnoticable), but i used a 30pt. I did not do anything to it! how do i change it back to the original size? i tried it on every picture and the problem still occured. HELP!

If the resolution of your image is very low, or you have set the zoom level for the image to be very small, text will appear smaller than usual.

If you have not flattened your image, you can select the layer with the text in it from the layer menu, hide all the other layers, select the offending text with your text tool, then adjust its size.