My ex-employer sent me a letter saying I got ₹68,000 extra during my PF refund. They want me to pay it back. Is this legal? I think they’re trying to trick me because the PF office says Form F19 was changed, but I don’t recall doing that.

It’s possible your former employer is correct. If your ex-employer can prove that the extra ₹68,000 was due to an error in the PF calculation, they are legally entitled to recover it from you. However, if you can demonstrate that you did not personally modify Form F19, you could dispute this claim.