Waveform issues

While typing in track info under “export”, one of my fingers hit a button on the keypad. I did not any changes until I loaded the next track to edit. There now is 2 colours on the waveform screen. 1 dark (outside 1/2) and the other light (inside 1/2). There’s also a type of rule at the 2 edges (left & right) of this screen. I can now adjust the waveform to flat or max. I, for instance cannot adjust my treble and base. Also, under “undo” there’s now “undo envelope”. This however does not change anything. Please help.

Does it look something like this:

If so, you may have accidentally pressed the F6 key (http://manual.audacityteam.org/man/multi_tool.html), in which case, press the F1 key, or press the “I” cursor button to go back to the normal selection tool

See here for more info about the tools: http://manual.audacityteam.org/man/tools_toolbar.html