how to separate data in cell into separate cells , sorted by value

hoping i can trouble someone on this forum for some help. i have spreadsheet which has been exported from an online registration system. currently, one of the cells contains a number of various values, separated by commas. i need to have each value appear in a separate cell - but all sorted according to the value. the values however are not all consistent . it's described more clearly in the attached document, but for example.
line 1 . column A: values a,b,d
line 2. column A: values a,c
line 3 column A: value d

how can i make each line have the same values appear in the same column
line 1. [column A: a] [column B : b] [column C: blank] [column D: d]
line 2. [column A: a] [column B : blank] [column C: c] [column D: blank]
....

thanks for your time !