The first thing to do is to try a different font.
If that doesn't work, reset the Type tool.
Get the Type tool and click the first drop-down arrow on the far left side of the Options Bar. It gives you an option to Reset the Type tool.
As a last resort, try rebuilding the Preferences by shutting down PSE.
Hold Ctrl Alt Shift as you restart (in Edit mode) and continue holding the buttons. (Mac: Cmd Opt Shift)
You'll get a pop-up window asking you if you want to delete your settings.