My macbook pro trackpad failed to click, but the fact it clicked during logging in suggested it was not hardware. After lots of efforts including reinstalling OS , whiched fixed it for a couple of days, i read the input here and guessed it was an error with thesettings thar coul be repaired by changing ot. But how to do that without cliicking? My bt mouse also failed. It turned out my old bt trackpad did not, and voila, everything is fine again after changing the settings.