Can an employer force you to repay lost/missing money?

Unless your employment contract and/or publicized terms/rules of employment (e.g. in the employee handbook) require employees to repay lost money, the company may not force you to do this. Employees must agree to such a "reimbursement" policy, either explicitly, or implicity, by continuing to work when they are told that is the policy and they would have to reimburse lost money.

On the other hand, they may fire or discripline you for the loss. And if they believe that you took it or were complicit in someone stealing it, they might choose to sue you for its return or report the matter to the police.