You could also use an array entered formula:
=RIGHT(B2,MATCH(",",MID(B2,LEN(B2)-ROW(INDIRECT("1:"&LEN(B2))),1),0))&","&MID(B2,FIND(",",B2)+1,FIND(",",B2,FIND(",",B2)+1)-FIND(",",B2))&LEFT(B2,FIND(",",B2)-1)
Here the text to reverse is in cell B2, and you enter the formula with the (Control +...