Unfortunately, Singapore is an at-will employment zone. That means that generally there is no right of recourse against termination, assuming that the employer has given notice (or made payment in lieu of notice - e.g if termination has a 1mth notice, they can just give you the 1mth salary).
You can try to cite unfair dismissal, however, that is only for a limited amount of cases. The types of unfair dismissal are listed below:
https://www.mom.gov.sg/-/media/mom/d...068A2 301AB86
However, take note. Generally wrongful dismissal will only lead to compensation and not a reinstatement of your job.