KPN sim is no longer working

Hello @Ishmeet, welcome.

It's possible that your simcard is too old or broken. In which case you need a new one.

However, there might be another possibility.

Do you have KPN Prepaid? If so, when was the last time that you have actively used your simcard? If you don't use it for 6 months, it’ll get blocked. The only way to unlock it, is by topping up your credit. If you haven't used it for 9 months, it will get blocked permanently. You won't be able to get your number back.