I did not report my Singapore CPF as a US greencardholder for years, I forgot about it,and was not eligible to withdraw it.Do i need to send in fbars for prior years?

For the FBAR's, you will need to report these for all the years the account balances exceeded $10,000.  Read this IRS website regarding delinquent FBARS. You can combine past FBAR filings into one report. Report here.

For the FATCA filings, if the account balance exceeded $50,000 on 12/31, there is a Fatca reporting requirement.  You can amend a prior year's return to include a FATCA filing but there could be a fine of $10,000, with additional penalties of up to $50,000 for continued failure after receiving a notice from the IRS. If you have a cause for the delay, you would then need to demonstrate it to the IRS, to avoid penalties. It's important to address late filings as soon as possible to minimize potential issues.

Hopefully, 2024, was the first FATCA reporting year so you don't need to face the penalties.