retrospective or prospective effect of amendments

it all depends on the wording and intention of the Legislature.

All Acts have a provision to say whether the Act is retrospective or prospective in effect. There is no separate law for that. And whether an Act is prospective or retrospective depends on the objective/purpose to amend that Act.

Sir, I do not have knowledge of law. Since I have read it somewhere which I am simply typing which may be useful in this topic.

"A law dealing with procedure in the absence of anything to the contrary is retrospective in operation. On the other hand, statutes taking away, impairing or imperiling substantive rights are ordinarily prospective, and it will be construed to be retrospective only if it is so made either expressly or by necessary implication. Girdhar Das Anandji v. J. M.  Patel. 1971 PLJR 66

Sir, this one is from a judgement which I am simply typing which may be useful in this topic

Article 318 saves validity of the Acts enumerated in the 9th Schedule with prospective effect from the date of enactment of the respective laws and not from the date of enactment of Article 318 or the inclusion of the Act in the 9^th Schedule or any subsequent amendment of the Constitution. See AIR 1955 SC 47

Law applies only prospectively unless it has been specifically made retrospective.

Dr Satyadeo Pandey v. State of Bihar, 1999 PLJR 280