What should I do if the month is not completed before the end of the compensatory fasting, and will my fasting be accepted, and how do I make up for the remaining day, and is it permissible to fast the day before Ramadan?

Whoever forgot the number of days they owe from Ramadan (definition) should fast what they predominantly believe will clear their obligation. If time is too short to make up the fast before the next Ramadan, they should make up what they can before it and complete the rest afterwards. They should also feed a poor person for each day they delayed without a valid excuse. There is no harm in fasting one or two days before Ramadan for those who have make-up fasts due. The acceptance of fasting is a matter of the unseen, and the Muslim must perform their acts of worship according to the Sharia (definition).