It happened on all the Autocad versions along the tears.I modify the PGP file, toolbars and CUI.After a while, some unrelated commands don't work, for example:apploadproprtiesand moreI use now Acad 2014

I would restore the original versions of all those files (you did keep a backup copy of each did you not)?  Then I would open the altered versions of each file and give them a closer look to see where you may have messed up.