Reinstate, pronounced "rē-ən-ˈstāt," is a transitive verb and reinstatement is a noun. Its inflected forms are reinstated and reinstating. For example, "We should reinstate the policy against wearing hats in school" (transitive verb); "His reinstatement was final on Friday" (noun).
The first definition of reinstate is "to place again." For example, "The money was reinstated in his account" or "I heard that even though he was fired, he's been reinstated."
The second definition is "to restore to a previous effective state." For example, "The plug was initially pulled, but has been reinstated."
Reinstate in the business world means to "put back into active status." For example, "While her account had been canceled for nonpayment, when we received her check we reinstated it."
Reinstate in the Insurance field means to "return to active status after making reconciliation for failure to pay." For example, "He didn't pay his premiums, but because it was within the grace period, the insurance company allowed his policy to be reinsured if he paid all his past premiums, plus interest. The same type of procedure exists with mortgage firms as well.