It depends. The 120 days period does not reset as to Defendants named in the original Complaint. However, a new 120 day period applies to newly named defendants in the Amended Complaint. FRCP 1.070(j) states: "When a motion for leave to amend with the attached proposed amended complaint is filed, the 120-day period for service of amended complaints on the new party or parties shall begin upon the entry of an order granting leave to amend".
This reponse is for general purposes only and does not establish an attorney-client relationship. You should always seek the advice of an attorney to thoroughly review all of the facts and details of your particular matter before undertaking any course of action in reliance upon such a generalized response.
no it does not reset. The only way to extend the summons is by motion to extend it.
You should consult an attorney in your State at once.
I agree with the other attorneys but would just impress upon the importance of getting the time for service extended and serving process on the defendants. If you are past the 120 days you may be asked to show the steps you have taken to serve the defendants or possibly have the case dismissed.