Hi,
I'm assuming that you're unable to sort your report by date because the data type of your field is Text. If that is the case, you'll need to convert it first to a datetime field. Here's a formula that you may use:
CONVERT(DATETIME, [@field:], 101)
You'll need to add a Formula field first where you can insert the formula provided above. After that, you can now select that Formula field from the Sorting options on your report.
~JolliBeng