Is it legal to change locks on a house if your wife leaves and says she is never coming back?

Unfortunately without a restraining order she can legally gain access to the house.  You can and should change the locks and add an alarm to make it harder and at least alert you she came back.  In these situations it's better to call the police who often will try to convince her to stay somewhere else to keep things calm.  They would eventually allow her to stay, but it is usually enough to get people to avoid the situation.  The key is her financial situation, since she will likely try to come back when she runs out of money.  You need to file for divorce and settle with her as soon as possible to get things permanently separated.  

Yes you can changed the locks but she can break in, change the locks again, not give you a key and not face any legal consequences (same as you) as it is still her house since she is part owner. 

You were denied a restraining order so the Courts so I don't think you would also have a valid reason for locking her out. The Courts could even force YOU out if they think you are being unreasonable. 

IF you have proof of the abuse against your daughter and she is a minor (and its not just teen angst against one parent) then apply to Child Protective Services with that proof and have her restrained from approaching the daughter, therefore the family home. 

If you can't prove it to them either, then maybe what you think of as abuse just isn't enough to prove it to the authorities. In that case perhaps YOU need to rethink things. Are you overreacting? 

OR is this just your way of getting her out of the home? If that's the case shame on you. 

change the locks . Install ADT alarm system. Get a mean big trained guard dog as well. 

You sure can. Both you names are on the deed, so either one of you can change the locks. 

There's nothing illegal about changing locks. It's definitely occasionally necessary given such circumstances.

She's a co-owner of the home. She can break a window or crash down the door legally. Changing locks is only about making you feel better.

And, she didn't have to leave.

your house, your decision .............................