Can my husband change the locks without my knowledge?

He cannot just change the locks, call the police they should force him to let you in or in the alternative you can just break in, it is not a crime to break into your own house. Use of alawyer is recommended.

So, your only question is whether he can do something which he has already done? Well, he has already done that and it can be made to come back and haunt him. Hire an attorney.

There is so much information missing from your question, that it is very difficult to answer your question. You don't indicate what state or where in the other state you and the children were living during the school year, how you managed to register them for school in the other state if you weren't permanently residing there, whether they were residing there with you or a friend/relative, whether your name is on the title to the house as an owner or co-owner, how long you've been married, and other important facts. Generally, if you are legally married and the marital home is your permanent residence, then your husband would not generally be able to unilaterally change the locks. However, it is unclear from your question whether or not the marital home is still your permanent residence, or how long you have been away from it. Depending on your answers to these questions, you may potentially be within your rights to have a locksmith let you back in and cut you a key, though this may not necessarily be the most prudent course of action. Besides, if you were served with a divorce action on May 7th, your response was due on or about May 27th, over a month ago. If you have not engaged an attorney to represent you, you should do so immediately. They can assist you with responding to the petition, addressing any default that may have been entered against you for not responding on time, and obtaining temporary relief, which may include but not be limited to temporary use of the marital residence on a joint or exclusive basis, among other relief. Consult with an attorney and discuss the specifics of your situation and your options. Do so immediately, as time is of the essence.

If your name is on the deed to the home he cannot change the locks.

I do not know what a limited divorce is; I have not heard the term before.You need to answer that Petition immediately, you probably need an attorney, if nothing else contact your county Legal Aid Office. You also need to file a Motion for temporary use and possession of the home.