PSE 15 - selection tool not working

all of a sudden, the selection tool and the magic wand are not working -- clicking on them shows a big circle with a cross in it - if I try to drag, it selects weird parts of the area.  I tried to change the size of the brush/wand etc but those appear also to be locked.   I use this tool all the time so would very much like a solution.  I'm sure I stupidly clicked on something or used a weird key combination but can't figure out what I did.

thanks for your help.