Are the prayer and fasting of one from whom madhy (pre-seminal fluid) was discharged, and who did not purify his clothes, valid?

Your fasting is valid, and you will be rewarded for it. As for your prayer, there is a difference of opinion regarding its validity, but the most preponderant view is that it is valid because avoiding impurity is a condition when one knows about it and is able to avoid it. You were unaware of the impurity's presence, as you thought the garment was pure.