I have replaced the battery, but it didn't work. I've tried to reset the watch, but it didn't work. What have I to do to reset the WV-57H after a battery replacement?

This is a simple spring clip. At the end nearest the wrist strap there is a hook clip. Insert a small, thin pin and hook the lowest edge outwards and the strap should spring free.
Try the video link below, (at 2:45 minutes). It's a slightly different watch but the method is the same.

https://www.youtube.com/watch?v=8GI-xfBXHj4&t=261s

Try the battery first. Make sure to do the all reset inside of the watch after changing the battery. If it is not the battery send it to Casio. They may change out the complete module.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwi3ubnCjK76AhUYBDQIHdsDAbwQwqsBegQIBRAB&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DeRy0JlsjfqQ&usg=AOvVaw3hOvdMy7BXU6XfkxuFHigB

mcdevito75 here, I'm figureing you"ve changed the battery, Pressing the MODE button should re-start your watch. If you didn"t change the battery and your watch just stopped, try pressing the MODE or any button to re-start the watch. If nothing, change the battery and repeat the above instructions.

Click on my profile (escapement), then click on Tips and Tricks. There you will find link to all Casio watch manuals.Rate me, please

You can get instructions from the Casio web site.

Go to the casio web site "casio.com".

Select "support" and the "manuals", watches;

Accept terms

Select "watch manual archive"

Read the number of the back of your watch and enter it into the search box

Click on "search" and the download your instructions.

Check out my TIPS here and you will find out how to do that

this is the pdf for the instruction manual

http://ftp.casio.co.jp/pub/world_manual/wat/en/qw2555.pdf

If you look at the watch from the side, you'll see that there's a two-part metal piece on the underside of the watch on each side.  The metal piece is a spring-loaded pin going through the strap which is holding on a larger metal piece.  You need to get another small pin (or an eyeglass screwdriver might work) so you can poke in the end of that spring loaded metal piece, which will allow you to slip off the larger metal bracer.  Then you can poke the spring-loaded pin entirely out of the strap and it will be freed entirely.  
To help you visualize what you are doing, the spring-loaded pin operates similarly to a toilet-paper roll - you need to compress the pin so you can slip off the larger metal bit, then take out the pin, which will free the strap.

Try this link and type in your module number found on your watch and you should be able to download your watch's manual.
http://world.casio.com/wat/download/en/manual/